Board Game

Explanation:
In this comic, Cueball is shown explaining the rules of a board game to three other players ( Hairy , Ponytail , and Hairbun ) of a local board game club – a hobbyist group that gets together to play board games. However, the board game Cueball is explaining is actually his own creation which is designed to trick the club into preparing his income tax return. The caption indicates that Cueball does this every year, which makes this comic reminiscent of the My Hobby series.
An income tax return is an annual document which most adults (and some teenagers) in many countries must prepare and submit to the government agency responsible for tax collection. The document sets out that person's income for the year, along with offsets including deductions and credits, and calculates the amount of income tax the person is required to pay to the government (used by the revenue service to compare it to the value that person had actually paid).
The return requires understanding of a number of forms which may seem complicated to those not familiar with them. It is an annual task that is stereotypically met with confusion and disdain. Many people hire professionals to prepare their taxes. More recently, software-based solutions that walk the user through a series of more understandable text-based questions are available to aid taxpayers in completing their returns; however these are not always ideal for those with complicated returns.
In this comic, Cueball has developed his alternative method of tax preparation which utilizes the collective intelligence of several board-game-club players, and also capitalizes on the fact that members of such a club are likely very competitive and eager to succeed at board games. As a result (as the title text suggests), Cueball thinks the board game players are more thorough than the tax preparation professionals he has previously used. Such professionals would prepare perhaps hundreds of returns per year and as a result, might indeed be less thorough with each individual return which may all be viewed as fairly simple and repetitive by the professional.
Among the rules Cueball explains are references to "allowable deduction" cards which presumably reference certain deductions which are allowed on income tax returns to lower the net income (resulting in lower taxes). For example; a portion of certain medical expenses are permitted to lower one's income in recognition of the fact that using one's income for medical expenses is somewhat non-discretionary. Similarly, certain charitable donations are permitted as deductions to encourage such donations.
In Cueball's game, players must match the deductions with other cards to preserve their full "point value". This appears to be a reference to the desire to capitalize as much as possible on the value of a deduction by taking the deduction against income which would otherwise incur the greatest tax, and ensuring that the full amount of the deduction can be used. A deduction of $2,000 against income of $1,000 would waste half the deduction.
In gaming, tokens are small playing pieces which may represent various things, depending on the game. In many board games (e.g. Monopoly ), tokens represent the players themselves. In other games, such as Magic: The Gathering , tokens can represent creatures or other items in a player's inventory. Cueball references "dependent tokens" which appear to be game tokens representing Cueball's dependents. Dependents are individuals for whom the taxpayer is entitled to certain deductions and credits, often related to expenses incurred to care for the dependents.  Most commonly, dependents are the minor children whom the taxpayer is required to support financially, but in the United States (where Randall lives) a person can claim a qualifying child as a dependent as long as the qualifying child lives with the claimant and is not self-supporting, even if the claimant is not the person who supports the qualifying child, and a person who voluntarily supports another (without being required) may also qualify to claim the person. Also, U.S. law usually does not allow a person's own spouse to be claimed as a "dependent", even when financial support is required.
Note that while Cueball states he "tricks" his board game club into doing his taxes, in fact his use of clear tax terms ("allowable deductions", "dependent") for naming different tokens and elements of the game could suggest that the players knew what he was doing but going along with it because they just enjoy playing board games, such that even doing a tax return – often considered a boring mind-numbing chore – within the format of a board game would be something they would enjoy doing. (On the other hand, it's possible that the players don't realize that the game involves preparing Cueball's own tax return.) Alternatively, the comic may be comparing the tediousness of some board games to that of doing tax returns. It is noted that there are board games on a variety of unexpected topics which might seem like boring subjects for a game. For example, there are several games designed to simulate the stock market and investing. The popular video game Farmville is often joked about having created a successful game out of a job most people would find unpleasurable. This suggests it might actually be possible to create an board game enjoyable to some people from the process of preparing a tax return.
This is one of several xkcd comics that suggest going to comically extreme lengths to avoid doing something (in this case, his taxes) that might have been simpler to do normally than the way Randall proposes. In this case, Cueball suggests that his motives may actually be to get the most thorough preparation possible, rather than to simply find a way to get the task done. There is actually a pretty solid basis to for this.  Both gamification and crowdsourcing have been shown, in at least some cases, to produce results that can match or exceed those produced by professionals. For example, the University of Washington created an online game in which users tried to optimize the folding of protein structures. The results produced by players produced useful new structures more quickly than computer simulations were able to. In this case, the work is being done by people who presumably have at least some enthusiasm for games, and who are likely competing with one another for the best results. Randall can then use the best outcome (that created by the winner) to optimize his own tax return.
A similar situation of Randall secretly exploiting someone's interest for his own purposes occurs in 1323: Protocol .
And another board game can be found at 492: Scrabble .
This was the first time Randall made a comic about people having trouble understanding the US tax system. Since then he has two years in a row made comics in relation to an approaching tax day. See the title text of 1805: Unpublished Discoveries and the entire comic 1971: Personal Data .
[Hairy, Cueball, Ponytail (reading something), and Hairbun (holding some cards) are sitting around a table. There are several other objects on the table.] Cueball: ...Now, this pile is "allowable deduction" cards. You match them with cards in your hand to preserve their full point value. Cueball: Over here are "dependent" tokens...
[Caption below the frame:] Every year, I trick a local board game club into doing my taxes.


Kitchen Tips

Explanation:
This is another one of Randall's Tips , this time with a series of Kitchen tips.
In this comic, Cueball appears to be hosting a show (or be in an ad) giving out kitchen advice. He starts with a reasonable tip to use a meat thermometer instead of guessing when meat is cooked. His later tips, though, are little more than telling how to complete normal kitchen activities performed using common sense. Moreover, in most cases he repeats "If you're anything like me," suggesting he's actually done these things in his kitchen. This is a parody of many commercials and infomercials that imply their consumers have no basic motor skills or common sense in order to make their product more appealing.
The first tip he gives is reasonable because, though the use of a meat thermometer is fairly well known, not everybody goes to the trouble of using one. To determine if meat is done cooking, one can either guess or use a meat thermometer to check that the internal temperature has reached the correct level to render meat safe for consumption. Many people don't own a meat thermometer and rely on an alternative solution that doesn't require special equipment (such as testing by feel, cutting the meat open to check its doneness, checking the color of the juices after pricking the meat with skewer, or simply guessing).
The second panel shows that Cueball throws away dishes and buys new ones every time they are used. This is perfectly normal if the plates are disposable plates made of paper or Styrofoam (though not exactly environmentally friendly), but we see his trashcan is filled with chipped glasses and ceramic plates. Naturally, this would be a very expensive practice. The virtually universal chore of "washing the dishes," is one Cueball presumes the audience is heretofore unaware of.
Cooking on a stove is typically done placing the food into a pot or pan which is placed on the burner [ citation needed ] . Cueball seems to suggest that the use of a pan is a tip most people would be unaware of, suggesting that most people cook eggs directly on the burners themselves, a method that is likely to burn the food and create a great mess.  Cueball's stove has T-shape raised burners (probably gas, but might be electric), making the task very impractical, though owners of glass-top electric stoves could conceivably cook directly on the glass surface.
Ice is usually made by filling an ice cube tray with water and leaving it in a freezer for several hours. Cueball, however, sprays a hose directly into his freezer compartment and quickly slams the door shut to trap some water inside. (This would work somewhat better in a chest freezer, which has a door on the top, as it could be filled with water and the door would not need to be closed to trap the water inside.) While this unorthodox method will make ice, it will result in a large sheet of ice on the bottom of the freezer. More importantly, it will also make it impossible to actually use the freezer to hold anything else (unless you were to put anything in beforehand and you don't mind breaking through a block of ice to get it out). Also, ice expands as it cools (it is one of the few substances with a negative coefficient of thermal expansion), and its expansion might push the freezer door open.
The title text, a household tip , suggests using toilet paper a few sheets at a time, which is how most people use it. Cueball, however, seems to suggest that most people use the entire roll as a single object without unspooling it and then flushing it whole, using at least one roll each time they use the bathroom. This is economically impractical, and is prone to clogging the toilet and the plumbing if you throw the toilet paper away by putting it into the toilet and flush it.
For more household tips like the one in the title text, see the sequel to this comic: 1715: Household Tips .
[Cueball at a kitchen counter, with various items, holding a meat thermometer.] Cueball: If you're anything like me, you may have trouble telling when meat is fully cooked. Cueball: Instead of guessing, try a meat thermometer!
[Cueball at a sink, holding a dirty dish, with a trashcan next to him full of broken ceramics and glasses.] Cueball: If you're anything like me, you probably throw away your plates and glasses when they get dirty. But if you clean them, they can often be used again!
[Cueball cracking an egg over a pan on a hot stove.] Cueball: Making scrambled eggs? Put a pan under them! Cueball: It's easier, and it keeps your burners clean.
[Cueball holding a garden hose, spraying it into the freezer compartment of a freezer.] Cueball: If you're anything like me, you make ice by spraying a hose into your freezer and then slamming it shut. Cueball: But there's a better way...


Synonym Movies 2

Explanation:
This comic made a series out of its predecessor as it continued the idea from 1563: Synonym Movies with a new set of movie series. As with the previous comic, the titles aren't always direct synonyms with the original (Indiana Jones as Professor Whip ), but now it seems to be even more exaggerated, sometimes making synonyms of the plot synopsis instead of the subtitle ("Vitamin Water" refers to the Fountain of Youth rather than the Stranger Tides ).
This set includes Wandboy ( Harry Potter ), Puncher ( Rocky ), Tropical Boaters ( Pirates of the Caribbean ), and Professor Whip ( Indiana Jones ).
The is in Another Movie title in the Professor Whip series differs from the other titles in that it does not reference the plot of the movie. The more dismissive reference may be due to Indiana Jones and the Kingdom of the Crystal Skull being poorly received by fans of the series.
The title text is a reference to the TV series Game of Thrones , based on the book series A Song of Ice and Fire .  All of these titles are direct synonyms, but such that they remove most of the meaning from the titles.  For instance, nobody actually cares about the physical object of a throne, but the political power it represents.  Birds eating in general have a very different implied meaning than crows feasting specifically, as groups of crows only gather to eat when there is a lot of food, such as a corpse, and as such have a strong cultural association with death and slaughter.
SPOILER ALERT! Many of these explanations contain information revealed during the movie.
[22 DVDs on a shelf in four groups. All DVDs are labeled in black on light grey. Text written so it is supposed to be read when the DVD is lying down.] [First group of 8 DVDs. All standing straight.] Wandboy and the Magic Rock Wandboy and the Hidden Room Wandboy and the Fugitive Wandboy and the Burning Cup Wandboy and the Firebird Club Wandboy and the Book Owner Wandboy and the Magic Stuff (1/2) Wandboy and the Magic Stuff (2/2)
[Second group of six DVDs. Five standing straight, last on the right leaning against the rest.] Puncher Puncher II Puncher III Puncher IV Puncher V Puncher Lastname
[Third group of four DVDs. First and last standing straight, others leaning on first.] Tropical Boaters: Spooky Boat Tropical Boaters: Angry Wormface Tropical Boaters: Boats Everywhere Tropical Boaters: Vitamin Water
[Fourth group of four DVDs. Three standing straight, second from left leaning on first.] Professor Whip and the Box of God Professor Whip and the Scary Church Professor Whip Looks for a Cup Professor Whip is in Another Movie


Magic Tree

Explanation:
This comic features a running theme in the xkcd comics, Beret Guy 's naive and/or odd ways of thinking. In the beginning of the comic, Beret Guy shows Megan what he believes to be a tree, and explains that it grew there because he placed magic beans in that spot yesterday. This is a reference to the fable " Jack and the Beanstalk ", where the protagonist plants several magical beans he acquired, resulting in a beanstalk growing which ascends into the atmosphere. Megan, however, tells Beret Guy that the "tree" is actually a cell phone tower . Beret Guy disagrees, pointing out that it has branches, to which Megan tries to explain that this was in an attempt to make the towers look like trees . She gives up, however, as Beret Guy has already begun climbing the tower, or because she fears that giving this explanation would only add fuel to the fire that is Beret Guy's imagination.
Later, Megan complains that her cell reception has disappeared. Beret Guy responds by saying that he had to cut down his "tree" because there were "scary giants with yellow helmets" in it (presumably, construction workers). This mirrors, again, the "Jack and the Beanstalk" fable, where the protagonist has to cut down his beanstalk to prevent the giant, whose lands the beanstalk connects to, from climbing down and chasing him. In reality, the "giants" were probably utility workers.
The title text suggests that, over time, trees will evolve to start looking more like cell phone towers in a form of mimicry in order to avoid people cutting them down. Mimicry is where a creature copies the appearance or behavior of another in order to confuse predators. In this scenario, the more defenseless trees attempt to mimic cell phone towers, which have the defense of people not wanting to cut them down or they would lose cell service (and likely a significant amount of money through fines) and because of society's general respect for the property of others, as well as the dangers of electrocution or radiation. This is similar to the counting pine ,  a tree in Terry Pratchett's Discworld series that evolved to display its age with numbers on the outside (in the bark) in the hope that humans would not cut it down and count its rings. Of course now humans hunted it down trying to find a tree with numbers that would fit their house number instead, thus quickly rendering the trees almost completely extinct. (See the tribute to Terry in 1498: Terry Pratchett ).
Convergent evolution deals with multiple species acquiring similar characteristics to fulfill their role (such as dolphins and sharks both having a streamlined shape to swim fast) due to the species' common need to adapt to similar environments or tasks. Randall uses the term to describe the convergence in the appearances of cell towers whose design has "evolved" to include tree-like branches and trees which he predicts will evolve to resemble cell phone towers. Each of these "evolutions" would be for the purposes of camouflage, although the cell towers "evolve" by human design for purely aesthetic reasons and the trees would evolve naturally for self-preservation. This would therefore not be a true example of convergent evolution. It more closely resembles Batesian mimicry, or the evolutionary process by which a species remains noticeable, but treated as something it is not.
[Beret Guy and Megan stand next to a large pole with a note on it. Beret Guy points at the pole.] Beret Guy: Check it out! I threw my magic beans on the ground here yesterday, and this big tree appeared!
[Zoom out, the pole is revealed to have branches. Around the pole are trees about 1/9th of the height of the pole.] Megan: That's a cell tower. Beret Guy: No way - it has branches! Beret Guy: See? Beret Guy: I'm gonna climb it!
[Same as frame as the first. Beret Guy starts climbing the pole.] Megan: No, they just put those there to make it look- Megan: ...Never mind.
[There is a caption in a small frame inlaid at the top of the last frame:] Later... [Megan looks at her phone while Beret Guy walks towards her holding an axe.] Megan: Why do I have no signal? Beret Guy: There were scary giants with yellow helmets in that tree! Luckily I cut it down before they ate me.


Engineer Syllogism

Explanation:
A syllogism is a logical argument where two or more propositions lead to a conclusion through deductive reasoning . For example, one of the best-known syllogisms is:
In this comic, Cueball is an engineer who is attempting to make the following syllogism:
Since most engineers are purportedly good at math, proposition 1 seems to be true. It is also loosely true that the stock market is made of numbers, but only in the sense that every system can be given a post-hoc numeric characterization; the dynamics of the stock market are primarily human-driven. In this comic Cueball thinks that his skill at math will help him beat the stock market. Little does he know that the system can be unpredictable, so he ends up losing money as the financial instrument he's invested in loses value. This is due to the financial markets being largely controlled by humans making emotional decisions and not some calculable reason or logic.
Even if the propositions "I am good at understanding numbers" and "The stock market is made of numbers" were true in Cueball's interpretation, Cueball would still be wrong to conclude that "I am good at understanding the stock market": this would be a fallacy of the undistributed middle (with the first premise being more accurately stated as "I'm good at understanding things made of numbers") and a fallacy of composition (with the implicit third premise "if I'm good at understanding the components of a system, then I'm good at understanding the system"). The problem is that proposition 1 seems to say "I am good at understanding all math". However, the "all" is not present, so Cueball may not necessarily understand the math underlying the stock market.
This comic is also related to the 1998 movie Pi where the main character repeats to himself several times his assumptions that the world is all numbers, and thus he, a great mathematician, should be able to predict the stock market, which is all numbers. He believes that maybe his work on patterns in pi will provide some deeper insight into the patterns in the stock market, a project that drove his mentor crazy and may in fact be making his computer self-aware.
The title text talks of the scenario where it was Cueball who causes everyone involved in the financial system to lose their money. This could refer to a scenario in which Cueball figures out a way to extract large quantities of money from the stock market, causing a sudden, major decline in everybody else's wealth, or that his involvement has caused literally everyone, including his own, stock market assets to lose their value. This is possible since there is no conservation of value for the stock market. The value of a particular stock is determined by a majority that is willing to trade it at a given price.
The release date of this comic makes it highly likely that it refers at least in part to the 2015 Chinese stock market crash which largely affected most other world financial markets, particularly during the week of August 24–28, during which this comic was published.
Two, less likely, interpretations of the title text have been suggested:
This scenario has been mentioned before, in the title text of 592: Drama .
[An white frame with text inside an underbrace and an overbrace.] An engineer syllogism
[Cueball is at his desk in front of his computer, with his hands on his knees, thinking.] Cueball (thinking): 1: I am good at understanding numbers.
[Cueball takes one hand to his chin, still thinking.] Cueball (thinking): 2: The stock market is made of numbers.
[Cueball lifts both arms from his legs, still thinking.] Cueball (thinking): 3: Therefore I– Wow , where did all my money just go?


Car Model Names

Explanation:
In English, letters like X and Z are rarely used in the common vernacular. Marketers have found that names with these infrequently-appearing letters sell more products.
Scores
There are two explanations for scores. Both of them share the fact that Randall must have used a car-name database to calculate letter frequency in car models.
There are 19 positive scores and 17 negative scores, which is interpreted differently in each explanation.
Score(x) = Frequency_in_cars(x) - Frequency_in_English(x)
This formula generates a positive number if a letter is more common in car models than in typical English (as X) which Randall then calls carlike. The formula generates a negative number if a letter's relative frequency in car models is lower than in typical English (as O) and Randall calls it English-like (more suitable for readable text). The letters F and B, with scores of 5 and -5, respectively, are about as common in English as in car models. With this nomenclature, the most English-like letter is Y because, while not the most common English letter, it is apparently extremely rare in car models. The most common letter in ordinary English is E, which is (presumably) fairly common in car models.
Score(x) = Frequency_in_cars(x)
It seems that Randall arbitrarily used positive and negative numbers: if a letter is very common in car models (as X) he calls it carlike. If a letter is very uncommon in car models (as O) he calls it English-like. With this nomenclature the most English-like letter is Y, but actually Y is the least carlike letter. The most common letter in ordinary English is E. Y on the other hand is just in the middle (place 13), which can't be called English-like.
Algorithm for the index
Randall devised an index for car models which is the score average divided by 10.
Example
We take 2Chainz and add the scores of its different numbers and letters: 6 +27 -44 -14 -21 -46 +83 = -9
Average is -9/7 = -1.29 and divided by 10 it's -0.129 or -0.13.
Names to avoid
Potential Hits
Note that Randall gives the symbol × the value of 126, which means he equates it with the letter x.
index(3×3Cutrix) = (+55 + score(×) +55 +27 -68 -18 +8 -21 +126)/9/10 = 3.22. This means that the score of the symbol × is 90×3.22 - 164 = 125.8
Title text
As mentioned in the comic, the index for the word "climax" is 2.48. However, applying the index to the phrase "sexclimax" yields a value of 2.72, higher than that for "climax".
Certain letters and numbers are used disproportionately often in car models compared to regular text. (see:"Rev-4 cr-x x3 G6 Maxx")
Letter and number scores based on relative frequency in car model names Carlike 60 6 55 35 74 6 27 5 27 64 32 12 19 40 8 15 41 126 83 0 1 2 3 4 5 6 7 8 9 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z English-like -74 -58 -67 -37 -14 -5 -21 -45 -44 -21 -46 -80 -27 -18 -68 -20 -90
Based on these scores, here are a few suggestions for car companies: (with average letter scores)
Names to avoid Potential hits Honda 2Chainz (-0.13) Honda 3Chainz (0.57) Mitsubishi Fhqwhgads (-0.62) Subaru Andre3000 (1.30) Kia 49AndGothy (-2.96) Suzuki Sexism (1.82) Chevrolet Niceguy (-3.09) Lincoln Marxism (2.17) Oldsmobile GoodWood (-4.44) Hyundai Climax (2.48) Infinity Toothy69 (-4.51) Porsche Zizek9000 (3.06) BMW Outhouse (-4.85) Lexus 3x3Cutrix (3.22) Volkswagen Woodpony 7OH7 (-5.70) Acura PizzaJazz (3.56) Chrysler Uh Iono (-5.65) Ford SixAxle 4x4 (3.95) Nissan Doody (-5.84) Toyota Cervixxx (4.85)


xkcd Survey

Explanation:
As the comic image states, it links to a survey created with Google Forms , containing a series of questions. The questions range from mundane typical survey questions such as “Do you have any food allergies?”, to rather strange, such as “Fill this text box with random letters by randomly mashing keys on your leopard.” (See 1530: Keyboard Mash ).
The stated goal of the survey is to “create an interesting and unusual data set for people to play with”. A strange data set is a ripe opportunity for a sampling of readers. It's also supposed to be “a search for weird correlations” – presumably the goal is to be able to say things like “people who have been skydiving are (more/less) likely than average to dislike cilantro”. (See also 882: Significant about finding presumably-spurious correlations between unrelated data.)
If the data is ever released, this explanation will be updated, but as of April  2022, this has not happened.
HTML image maps is a technique for marking up areas of an image on a web page, such that each area can be a link without the whole image being a link. Randall could have used this type of image map to make only the “Click here to take the survey” button be a link, and none of the rest of the image. But he cannot get the hang of it (or knowing his skills, does not wish to take the time to learn it). Not getting the hang of HTML image maps was also referenced on the banner for his book tour for the what if? book
The title text is a joke off of Big Data , which is a name for analysis of a set of data that includes a huge amount of information. He also says "for a big planet" because the Earth is big. [ citation needed ]
The survey is closed, and the questions replaced with the text: "The xkcd survey is now closed. Thank you for all your answers! Response data is being collected and will be posted soon." As of February 2022, the same caption is still there, with no indication of exactly how soon the data is intended to be posted. (Apparently, Randall crashed google forms, so the data is taking a long time to be retrieved (see this reddit thread) - much like his breaking of Wolfram Alpha ] during answering a reader's question on what if? )
A recreation of the survey can be found here on Google .
The recreation's data can be found live here.
It started with the following statement:
This is an anonymous survey. After it's done, a database of everyone's responses will be posted.
There's no specific reason for any of the questions. The goal is to create an interesting and unusual data set for people to play with. This is obviously not going to be a real random sample of people, but in the interest of getting cooler data, if you're sharing this with friends, try sending it to some people who wouldn't normally see this kind of thing!

WARNING: This survey is anonymous, but your answers WILL BE MADE PUBLIC. Depending what you write, it's possible that someone may be able to identify you by looking at your responses. None of these questions should ask about anything too private, but don't write anything that you don't want people to see. If you're not comfortable answering a question, just skip it.
Note: The order of the possible answers (the list of possibilities) was random, and changed every time the page is reloaded. So do not try to fix the order here below...
[A simple comic with text only. The click here part is inside a black frame.] Introducing The xkcd Survey A search for weird correlations Note: This survey is anonymous, but all responses will be posted publicly so people can play with the data. Click here to take the survey Or click here, or here. The whole comic is a link, because I still haven't gotten the hang of HTML imagemaps.
This strip was referenced upon the availability of preorders for How to: Absurd Scientific Advice for Common Real-World Problems . A new banner appeared at the top of the site to announce that preorders were available; at the right of the banner was a blue box labelled "Click here to preorder", followed immediately below by "Or click anywhere. I still haven't figured out HTML imagemaps."


Cyberintelligence

Explanation:
Ponytail presents a FY2015 ( Fiscal Year for 2015) budget for cyberintelligence , but is then interrupted with a snide remark about the prefix cyber .  Although it is not specified what organization the budget is for, the size of the budget ($8.1 Billion) is large enough to suggest that it must be a large government organization such as the United States Department of Defense.
This comic illustrates that some organization spends obscene amounts of money on their "cyberintelligence" budget, yet all that spending appears not to have informed them that the prefix "cyber-" fell out of fashion years ago. That the prefix could annoy experts were already used in the title text of 1084: Server Problem .
The prefix "cyber" is derived from " Cybernetic ," which comes from the Greek word κυβερνητικός , meaning skilled in steering or governing. Cyberintelligence could also be called cyber spying i.e. spying in the digital world, one of many "new" words with the cyber- prefix . Many were invented in the 1980s and 1990s, following the example of " cyberspace ", popularized by William Gibson in 1982.
If cyberintelligence departments were given names today, they might be called Internet Intelligence, Virtual Intelligence, Data Intelligence or Online Intelligence departments.
This may be due to the fact that government organizations are typically named by middle-aged or senior officials who are generally less likely to be familiar with the current trends in technology language. They are more likely to stick to the words that were used when they first learned about the technology. Such organizations, being bureaucracies, are also unlikely to change their name.
The title text continues the joke by implying the organization learned about the demise of "cyber-" yet failed to process or analyze that data. It is a common problem among intelligence organizations to gather "raw information" (such as photos, or reports from spies) but be unable to make use of it because there wasn't time to process the information into intelligence by determining what it means. This is particularly true for intelligence gathered by or relating to computers, as they can generate data far faster than people can review it. It may also be a reference to the previous comic, which was a link to a survey for xkcd readers.
"Cyberspace" and " cybernetics ", illustrated here , are two of the most common words with that prefix (Cyberspace 6 times as prevalent as cybernetics at their peaks). "Cyberintelligence" is shown here . Cyberspace was used 4000 times more often, although the more common spelling splitting it in two words "Cyber intelligence" was 1.35 times more used than in one word. But even combining these two versions cyberspace is still used more than 1700 times as often.
[Ponytail, pointing at a chart to her left, with text and two curves on a graph, is talking to someone off-screen to the right.] Ponytail: Our overall FY2015 cyberintelligence budget was $8.1 billion- Off-screen voice: -Yet it wasn't enough to pick up on the fact that no one else has used the prefix "cyber-" for like a decade? Ponytail: Shut up.


Trouble for Science

Explanation:
The comic highlights the fact that several well-publicized scientific critiques have recently been published that raise questions about some commonly accepted scientific methods. For scientists, these critiques serve as reminders of the dangers of overconfidence in any method, hopefully leading those who have naively accepted results to remember that any scientific conclusion is by its very nature tentative and limited by methodological reliability. However, popular press reporting of these papers may lead a general public of modest scientific literacy to the impression that science might be in trouble, as implied by the title. Some of these methodological issues and shortcomings are well known in the scientific community but are – for better or worse – the best toolkit science has at its disposal today. This is however greatly exaggerated by the last (fictional) headline, which suggests that Bunsen burners in fact have a cooling effect, which is of course absolutely ridiculous, but would nevertheless change one more fundamental scientific belief drastically. Additionally, each headline contains irony or a double meaning for comical effect.
The titles of five scientific articles are shown:
Many commercial antibody-based immunoassays are unreliable
This sentence is true. See Kebaneilwe Lebani, Antibody Discovery for Development of a Serotyping Dengue Virus NS1 Capture Assay , 2014. In this Ph.D. thesis, 11 references are given.
Problems with the p-value as an indicator of significance
In empirical research, one is usually interested in effects, results and relationships in a population. However, for practical reasons, only smaller subsets of populations, called samples, are available to the researcher. Usually, an effect of interest is tested using a sample. The purpose of hypothesis testing is to determine whether the observed effect (or lack of effect) in a sample is a random artifact of our particular sample, or whether there is a good chance that it also exists in the population.
Generally, a null hypothesis states that there is no effect in the population while the alternative hypothesis states that there is an effect.
P-values are used in hypothesis testing. The p-value is the probability of observing an effect, result or relationship in your sample data, given that no such effect, result, or relationship exists in the population. It is based on the sample data and the particular statistic (such as sample average, t or F). A statistic is the result of a calculation based on the sample. A p-value can be calculated for each statistic of interest. Formally, the p-value is the probability of observing a test statistic equal to or greater than the one based on the sample data, given that the null hypothesis is true.
The threshold for p-value cutoff, α, is pre-specified (usually 5% or 1%, which is more conservative). When the p-value is lower to or equal to α, the null hypothesis is rejected in favor of the alternative hypothesis. When it is higher than α, the null hypothesis is retained.
The value used for α has been proposed by Fisher and is arbitrary.
The use of p-values as a measure of statistical significance is frequently criticized, for example in Hubbard & Lindsay . Randall has demonstrated this problem in the past in 882: Significant .
Overfeeding of laboratory rodents compromises animal models
Keenan et al. makes this case. Additionally, the word model takes on two meanings. In one sense, "model" can refer to a scientific description that makes sense of a phenomenon; in another sense, "model" can refer to an individual whose job it is to demonstrate fashions, typically fashionable outfits. Fashion models are notorious for being exceptionally thin, and so overfeeding would compromise their job as a model.
Replication study fails to reproduce many published results
A replication study is a study designed to duplicate the results of a previous study by using the same methods for a different set of subjects and experimenters. It aims to recreate the results to gain confidence in the results of the previous study as well as ensure that the findings of the previous study are transferable to other similar areas of study.
Randall is probably referring to this recent study described in Nature: Over half of psychology studies fail reproducibility test. It might also be a reference to at least 3 studies mentioned here: http://www.jove.com/blog/2012/05/03/studies-show-only-10-of-published-science-articles-are-reproducible-what-is-happening . There is also irony in the phrasing of the title because in biology replication is a form of reproduction.
Another possible interpretation of this headline is that a replication study, which may have successfully replicated the results of the specific study it was designed for, failed to reproduce the published results of many other unrelated studies. The headline is quite vague as to which results have been considered in this study.
Controlled trials show Bunsen burners make things colder
The theme of this comic is that commonly accepted scientific methods can be unreliable, and the joke here is that a Bunsen burner, a device intended to heat things, is newly discovered to always cool things instead, which would be absurd.
In theory, yes, putting a Bunsen Burner underneath an object that's already incredibly hot would, slowly, equalize the temperature between the flame and object resulting in cooling. Given that a Bunsen Burner burns between 1000 K and 2000 K, there is probably some methodological error if the testing materials were already much hotter than the flame (more than 2000 Kelvin). It's also possible that if the "controlled trial" involved a Bunsen burner that was not lit, but was turned on to allow gas to flow, it would have a cooling effect as the gas expanded from the line pressure to atmospheric pressure. Another alternative theory is that a cold substance, such as cold water or frigid air, was fed through the burner against a warmer object.
Alternatively, a trial could be set up to test something against a Bunsen burner on the one hand, and an even hotter flame on the other hand. As compared to that hotter flame, the Bunsen burner would not heat up the tested material as much, resulting in something being made "colder" than the alternative.
As in the previous headline, the key to understanding the joke here is to examine the headline's ambiguity, as no clue is given about how the trials were controlled.
(Title text) Careful mathematical analysis demonstrates small-scale irregularities in Gaussian distribution
This is another joke of a premise that is obviously untrue. The Gaussian distribution is a mathematical construct that is generally known as the bell curve or the Normal distribution. As it is an ideal mathematical construction, by definition, it cannot have any irregularities - similar to how the equation y = 2x + 1 cannot have small-scale irregularities. The joke probably alludes to the fact that many types of observations are frequently initially modeled as a Gaussian distribution, though on careful observation the actual distribution of outcomes will often deviate from a pure Gaussian distribution.
In addition, an experiment to test a Gaussian distribution will have a finite sample size, giving a non-exact Gaussian distribution. A possible paper submitted would conclude that this result is "approximately a normal distribution" with "small-scale irregularities". A news reporter without knowledge of statistics could easily misinterpret that this paper decisively concludes errors in the mathematical definitions (rather than coming from random error inherent in experimenting).
[Five panels, each with the top part of a scientific article, where only the title is legible. Below is the list of authors and subheading and text in unreadable wiggles.]
Many Commercial Antibody-Based Immunoassays Are Unreliable
Problems With the p-Value as an Indicator of Significance
Overfeeding of Laboratory Rodents Compromises Animal Models
Replication Study Fails to Reproduce Many Published Results
Controlled Trials Show Bunsen Burners Make Things Colder


Footprints

Explanation:
The comic is a satirical graphical representation of the inspirational Christian poem " Footprints ," which has been recounted in many versions and is of disputed authorship.
The basic idea of the poem is that the narrator looks back at scenes of his life and sees two sets of footprints, his and those of Jesus. During the most difficult times of his life, the narrator sees only one set of footprints and assumes that Jesus had left him during those times. In the climax of the poem, Jesus responds to the narrator that he saw only one set of footprints during the most difficult times of his life because Jesus was carrying him during those times.
The poem is seen by many as overly sentimental and is thus ripe for parody of this kind. The graph mockingly illustrates various times when Jesus or the narrator left the scene, or otherwise gives various reasons why the number of footprints may have been other than two.
"Ducklings imprinted on Jesus and followed Him around" is a reference to Konrad Lorenz 's experiments. Three ducklings followed Jesus and the narrator.
"Jesus disappeared for an evening each time a new Twilight movie came out" could mean that Jesus went to see the movie and left the narrator alone.  It could also mean that his support of people through their most difficult trials meant he had to carry a lot of emotionally scarred people.
"Got lost and followed our own footprints" may be a reference to " Winnie-the-Pooh " (1926), in which the titular bear and his friend try and hunt a "Woozle" by its footprints, actually following their own round and round a spinney, which also seems slightly childish for Jesus as traditionally portrayed. An alternate explanation is that they came to a dead end, and had to double back.
"Rode around with Jesus in captured AT-ST " is a reference to a two-legged combat "walker" from Star Wars. The implication is that Jesus would have participated in forcibly taking a war machine, which appears somewhat out of character.
The reference at the end to Jesus drowning in a patch of quicksand, and then the narrator simply going home, again subverts the poem's earnestness. "Going home" may be a reference to dying, implying that the narrator died without Christ, or that the narrator and Christ were not traveling anymore. It is also possible that this is meant literally, and the narrator actually went home.
The title text continues the parody by imagining that Jesus delivers the poem's climactic lines in stereotypical "bro" speak, a dialect perceived by many to be obnoxious. The reference to punching Jesus is possibly another reference to the poem's perceived excessive sentimentality. Another interpretation is that the narrator, like many people, dislikes usage of this lingo and punched Jesus as a result of this hatred. This might also be a pun on "totes;" with tote bags being used to carry things. The narrator punching Jesus might be because of his hatred for the pun.
Yet another interpretation is that Jesus' obnoxious way of explaining himself indicated dishonesty, meaning he did not in fact carry the narrator during the most difficult parts of his life. The narrator sensed this and punched Jesus in retaliation.
"There's one set of foot-p's cause I was totes carrying you, bro!" can be translated into normal English as  "There's one set of footprints because I was definitely carrying you, friend!".
An alternate explanation of some of the oddities of the strip is that "Jesus" is not Jesus Christ, but some guy merely named Jesus, as is common in some Latin American countries.
Using the Twilight movies as reference points, it can be determined that the span of the graph is from approximately early 2004 to late 2018, with Jesus' death in the second half of 2017.
The poem has appeared in xkcd before, at 1110 with coordinates 0.7601, -58.803.
[A graph is shown with a a single red line that runs through from left to right, showing different values at different times. Until the very end, the line always returns to the value 2, signifying two sets of footprints in the sand. The X-axis has a label followed by an arrow pointing right. The Y-axis has a label at the top, right of the axis, and numbers, one for each of the ticks from which five thin lines going horizontally across the entire graph. Every time the graph moves away from the value 2 there is an arrow pointing to the event and a label. The first two events has the same label. The only label below the line has five small arrows pointing to five small dips in the curve. All other labels only has one arrow pointing to one event.] X-axis: Time Y-axis: Sets of footprints 5 4 3 2 1
[The line starts at the value 2, then dips twice to the value 1. The two troughs are labeled:] Jesus carried me
[The line dips once again to the value 1. The trough is labeled:] I carried Jesus
[The line rises to 3 briefly, and is labeled:] Who was that guy?
[The line rises to 5 sharply, and then falls in a sharp staircase pattern, labeled:] Ducklings imprinted on Jesus and followed him around
[The line rises to 4, labeled:] Got lost and followed our own footprints
[The line dips for very short periods five times to the value 1. The first dip is between "I carried Jesus" and "Who was that guy?", the second between "Who was that guy?" and "Duckings imprinted on Jesus..." and the final three are all between the "Ducklings imprinted on Jesus..." and "Got lost and followed our own footprints". These five troughs share one label with five arrows from the same text:] Jesus disappeared for an evening each time a new Twilight movie came out
[The line dips to 1, labeled:] Rode around with Jesus in captured AT-ST
[The line dips and stays level at 1, labeled:] Hit quicksand patch. Jesus didn't make it :(
[The line dips to zero at the end, and is labeled:] Went home


I Could Care Less

Explanation:
However, linguists point out that the strict application of logic to an idiom is inappropriate: many expressions seem on the surface to mean the opposite of the meaning they are used to convey (e.g. "head over heels"), and they defend "I could care less" on those grounds . The psychologist Steven Pinker argues in The Language Instinct that the phrase is sarcastic (cf. "Big deal!"), while linguist John Lawler explains it as a "Negative Polarity Item," a phrase that is practically only used in negated form, allowing the explicit negation to be omitted (a pattern often found in French).
In this comic, Megan feels alone because there is unavoidable difference between her understanding of her own words and the listener's interpretation, so while she sees discussion of semantics as being of potentially high social and emotional value, she doesn't think it has objective value. However, ironically, at the end of the comic, the meaning of "I could care less" with regards to Ponytail's behavior is ambiguous: either Megan is brushing off Ponytail's pedantry because she doesn't care about it (she couldn't care less) or she is hurt by Ponytail's focus on the details of her words rather than the emotional cues she should have learned over the course of their relationship (she actually could care less).
The title text refers to another word often used in ways some consider incorrect: "literally" (see 725: Literally ). The sentence is also ambiguous, as it may mean that 'literally' or 'figuratively,' the speaker could or couldn't care less. Further, it implies that Randall considers the argument over whether literally may be properly used to mean 'figuratively' is petty in the same way. Later in 1735: Fashion Police and Grammar Police Ponytail is once again on the side of the grammar police and also in this comic the word literally is used.
Alternatively, it could mean that Megan cares too much about Ponytail's correction, considering her response to it.
In a further alternative, the title text could amount to a self-ironical evaluation on Randall’s part to the effect that he himself might be devoting too much of his time and energy to the meaning of the phrase in question, as evidenced by the comic itself.
The inverse image of Megan floating through space in the fourth panel, as well as her long introspection, is a reference to the five-part "Choices" series, starting at 264: Choices: Part 1 .
[The first three panels are slim compared to the next row below, and they only takes up the same space as the first two of the three panels below this row. Similarly the bottom row, also with three panels, take up less space, although more than the top row. But in this bottom row the empty space in the comic is to the left vs. to the right in the top row.]
[Megan and Ponytail are walking together, Megan in front holds her arms out to the side.] Megan: ...Anyway, I could care less.
[Zoom in on Ponytail holding up her hand (which can atypically be seen), finger pointing up.] Ponytail: I think you mean you couldn't care less. Saying you could care less implies you care at least some amount.
[Back to Megan and Ponytail walking, both have their arms down.] Megan: I dunno.
[The next panel supposed to be to the right of this is missing, instead the comic jumps to the next row. This fourth panel has inverted brightness, with a white Megan floating in a black void, with white text above her.] Megan: We're these unbelievably complicated brains drifting through a void, trying in vain to connect with one another by blindly flinging words out into the darkness.
[Back to Megan and Ponytail walking.] Megan: Every choice of phrasing and spelling and tone and timing carries countless signals and contexts and subtexts and more, Megan: and every listener interprets those signals in their own way. Megan: Language isn't a formal system. Language is glorious chaos.
[Zoom in on Megan's head.] Megan: You can never know for sure what any words will mean to anyone. Megan: All you can do is try to get better at guessing how your words affect people, so you can have a chance of finding the ones that will make them feel something like what you want them to feel. Megan: Everything else is pointless.
[They have stopped walking as Megan holding a hand out has turned around facing Ponytail.] Megan: I assume you're giving me tips on how you interpret words because you want me to feel less alone. Megan: If so, then thank you. Megan: That means a lot.
[Megan and Ponytail resume with their walking.] Megan: But if you're just running my sentences past some mental checklist so you can show off how well you know it,
[Megan and Ponytail continue walking.] Megan: then I could care less.


Advent

Explanation:
An Advent calendar is usually a means of celebrating the days before Christmas. Each day on the calendar is represented by a "door" (a flap of card), behind which is usually a picture related to the Christian nativity, a picture of commercial Christmas (e.g. a present), a small chocolate, or a small gift. This comic satirizes the concept by proposing such a calendar that would have one gift for each day one is anticipated to live. Such a calendar would be very morbid and existential. This is especially disturbing when given as a gift because it implies someone has put extensive thought into when the recipient will die.
In Cueball's case, assuming each square in the calendar represents one day, the wall he is facing is the entire present he received and the boxes just out of view follow the same pattern, the entire wall represents 16,800 days (a large grid of 12x20 smaller grids of 10x7 boxes: 12×20×10×7 = 16,800), i.e. just under 46 more years (16,800/365.25 = 45.99589).
Assuming that Cueball is a male from the US and the grid represents his life expectancy, according to American Official Social Security Actuarial Life Table for males, he is probably 31.9 years old . This would make Cueball almost exactly one year older than Randall , who was born October 17, 1984 making him 30.9 years old when he wrote this comic. Due to the non-linear shape of the mortality curve, the chance of Cueball making it to the end of his calendar is 57.7%, at which point he will need to get another calendar but with only 9.2 years worth of doors.
The title text refers back to a standard advent calendar by saying that the Christmases are specially marked; on a traditional Advent calendar, only the 1st to the 24th of December have doors, however in recent times, Advent calendars often also include an additional door for the day after Advent, Christmas Day. A few dozen may be any small number of dozens, and 3 5/6 dozens (46) is aptly described by a few dozen ; see 1070: Words for Small Sets . Any dictionary (for example Oxford Learner's Dictionaries ) says that a dozen may be an approximate number, not exactly 12.
A completely different advent calendar was mentioned in 994: Advent Calendar .
Similar calendars have been mentioned in the blog Wait But Why in the 2014 post Your Life in Weeks , and in equally geeky webcomic Abstruse Goose , in the 2008 post 936 Little Blobs .
[Cueball is looking at a large wall subdivided into a rectangular 20 x 12 grid, with each grid subdivided into 10x7 small drawers. Below the frame there is a caption:] Unsettling gift: Life expectancy Advent calendar


Squirrelphone

Explanation:
"Squirrelphone" is a compound word combining " squirrel " and " phone ".
In this comic, we see a squirrel pretend to be a telephone, only to bite Cueball when he tries to pick it up and use it as one. This is humorous because a living squirrel is not an appropriate creature to maintain a phone call [ citation needed ] . This could be seen as an example of mimicry in nature, or parasitism where one creature gains a benefit from another.
It may be an allusion to the vampire squirrel which was documented recently that allegedly 'attacks and kills' deer.  The comic follows the absurd conclusion that the squirrel uses mimicry to 'attack and kill' humans.  Cueball may be lucky to still be alive [ citation needed ] . Another possibility is that the squirrel thought that Cueball was trying to eat it because Cueball picked it up and put it near his mouth, so it bit Cueball in self-defense. If this is the case, then biting Cueball can be said to have worked, as Cueball did relase the squirrel, as shown in panel four. However, this fails to explain why the squirrel was imitating a phone, which would make a human more likely to pick the squirrel up, so Randall was more likely trying to reference the recent vampire squirrel documentation.
The sounds the squirrel makes correspond to the tones that the terminals make when you use the POTS (Plain Old Telephone Service) in the US:
Squirrels have been used frequently in xkcd, also in what if , where it has for instance been used as a cute animal to replace a drawing of something scary or unpleasant like in Blood Alcohol or Cannibalism . So this is some twist for the cuteness factor of squirrels in xkcd.
It may also be the case that "squirrelphone" is a reference to the popular web-mail software SquirrelMail .
The title text takes the joke further by showing the squirrel possesses another phone feature: that cordless phones need to recharge frequently, either by setting them at their cradles or by connecting them to a charger, in the case of mobile phones. When they sense the battery is low, they emit a beeping noise every few minutes. In this case, the stump is the squirrel's cradle. However, the reason that cordless phones beep when they are getting low on battery is in order to alert humans to move them to the charging cradle because the phones cannot move themselves. On the other hand, squirrels can move on their own without needing humans to pick them up, [ citation needed ] so the squirrel likely only does it in order to trick people into picking it up, which further suggests that it is a vampire squirrel.
[Cueball is approaching a stump with a squirrel perched on it. A ringing noise is coming from the squirrel's back.] Squirrel: Riiiiing Squirrel: Riiiiiing
[Cueball has picked up the squirrel and is holding it to his left ear.] Cueball: Hello?
[The squirrel bites Cueball's head.] Squirrel: Chomp! Cueball: Ow!
[Cueball holds his hand to his cheek while the squirrel leaps away, fleeing.] Cueball: ???


Tech Loops

Explanation:
The comic is about how much time a geek might spend on a computer just to maintain the system itself, rather than actually using it for something relevant. This can in the worst cases go all the way up to the point where maintaining the system becomes the main goal. Often the operating system (OS) needs periodic updates, which might break some apps which in turn need to be updated; apps themselves might need to be updated, which can create all sort of incompatibilities which the geek then needs to spend time fixing.  One term for this is " dependency hell ".
Most people consider computers as tools to achieve something else — e.g. to surf the web, play games, read news or balance their bank account — and they would rather not have to spend lots of time on maintaining the OS or the computer if they can avoid it.
Here, however, Randall finds he's spending most of the time using his computer just for the sake of maintaining the OS or the hardware on said computer. It's tools for the sake of tooling, rather than tools as helpers to build something else.
A hardware equivalent would be the RepRap Project : get a 3D printer and end up spending all the time printing 3D parts for itself instead of creating something else like toys or art.
An alternative interpretation is how a simple task can get maddeningly tricky because of the inherent complexity of the system. An example of this appears in 949: File Transfer , where the simple task of sending a file from one computer to another gets practically impossible despite having all kinds of cloud tools available, many of them designed to perform much more complex tasks with one simple click. In this view, the box labeled "things I actually want to use my computer for" could refer to simple actions like transferring a file and all the rest of the graph are unsuccessful tiring attempts to solve the problem by installing increasingly complex tools which end up not solving the simple problem properly. This is similar to this traditional programming joke .
In the title text Randall realizes that what he really wishes to do it often only to learn about and discussing new tools to improve the chain. So in this way it is for sure only a system to support itself. But on the other hand, then the box with things he actually wishes to use the computer for, is then not disconnected from the rest, but an integral part of it all.
Other comics about the same concept are 349: Success and 763: Workaround .
There are 18 boxes in the chart, but only 12 different texts. 16 of the boxes are interconnected. Two are not connected to any other boxes.
Here is a list of all the items explained individually:
The flow chart described: → means supports (key) Things I actually want to use my computer for [isolated box with no links into or out of, by any of the following] DLL needed by something → ? [two exits to unknowns] Library (1) → Awful hack from 2009 → Awful hack from 2009 → IRC for some reason → Awful hack from 2009 → (Loop) Awful hack from 2009 → Library (2) → Library (3) → Repository Awful hack from 2009 → Library (4) → Library (5) → Custom Settings → Library (6) → Library (6) → Chat Client → Repository Library (6) → Hardware Workaround → Hardware Workaround → VM → Chat Client → Repository Hardware Workaround → Awful hack from 2009 → (Loop) Library (6) → Tool (1) → Updater → Updater → Repository Updater → Library (6) → (Loop) Updater → Tool (2) → VM → Chat Client → Repository (Note the Repository node leads to nowhere)
[A flow chart 18 boxes linked (or not) with arrows going in several different directions. At the top is an arrow pointing to the right with text under. The rest of the text in the chart is written inside the boxes.] [Under arrow:] Supports
[Going from the top below the tip of the arrow and reading left to right and top to bottom the following text is written in the boxes that all are in some way connected with each other. The number of arrows going in and out of each box is noted behind the text in square brackets as [in, out]:] Updater [1, 3] Tool [1, 1] Tool [1, 1] Repository [3, 0] Library [1, 1] Library [2, 3] Library [1, 1] Chat Client [2, 1] VM [2, 1] IRC for some reason [1, 1] Custom Settings [1, 1] Hardware Workaround [1, 2] Library [1, 1] Awful hack from 2009 [3, 3] Library [1, 1] Library [0, 1]
[The last box in the lower middle is not connected to any other boxes but has two exit arrows pointing to two questionmarks.] DLL needed by something [0, 2] ? ?
[Box alone at the top right corner, with no connections:] Things I actually want to use my computer for [0, 0]
[Caption below the panel:] Every now and then I realize I'm maintaining a huge chain of technology solely to support itself.


Travel Ghost

Explanation:
In racing game , a " ghost " is a common term for the recording of a player's best actions. The recording is used to create a virtual racer that another player can compete against. The previous player is shown as ghostly and transparent, because it is only a recording of a previous game and it does not interact in any way with the game currently being played. Certain models of cycling also use this concept to motivate athletes while training.
A mapping app, such as Google Maps , attempts to plot the fastest route from one place to another, but there's no way to tell which route is really the fastest without testing it. So, Cueball has created an app that will simulate a number of different routes and produce "ghosts" from them. He hopes to use this app to discover the fastest route by competing against his ghosts like a racing game. He brags about this app to his friend White Hat .
However, the comic takes a turn for the absurd when it depicts actual ghosts competing with him, instead of simulations on his phone.  Soon enough, he is fired from work because one of his "ghosts" is more punctual than he is. And even worse his children apparently comes to prefer the more punctual "ghosts" over him as this version of daddy never misses their games. (The girls could be the same as those in the 1659: Tire Swing ).
In the title text this is even taken into the bedroom, although it is a different ghost than the one preferred by the children. This is likely a subtle reference to euphemisms for sexual climax, such as "arrival", with delayed ejaculation generally preferred.
It should be noted that this app would not guarantee the minimum travel time. The user doesn't find out which route was fastest until after the first ghost has arrived. But as the current traffic situation will have changed by then, that route will not necessarily still be the fastest.
[Cueball, holding a smartphone, is talking to White Hat.] Cueball: Lots of apps let you plan your trips using real-time bus, train, and traffic data.  They try to predict which route will be faster, but aren't always right.
[Cueball continues to talk off-panel. The text is above a map showing three possible routes with an overlaid Cueball on each; the top and the bottom route and Cueball are faded and the middle is black up until the black Cueball. After that this route is also faded. A black point on the right indicates the destination.] Cueball (off-panel): Instead of just planning , my new app lets you send "ghost" versions of you along different routes, simulating their travel using the real-time data
[Cueball, again talking to White Hat, holding the smartphone down.] Cueball: That way, you can see which route turned out to be faster in practice, Cueball: You can also race your past selves.
[Cueball is getting out of his car holding his smartphone in one hand and a briefcase in the other; A faded out Cueball bicyclist is in front of him to the right. At the top there is a caption in a frame: Soon... Cueball: Ugh, lost to the bike ghost again.
[Cueball with his briefcase is outside a door, holding a key card up to a key reader. On the inside of the door Ponytail is facing the door and points toward the faded version of Cueball also holding a briefcase.] Cueball: Hey, my key won't work Ponytail: I'm sorry, but we've decided to replace you. This floaty guy is much more punctual. Cueball: But...
[Science Girl and another girl with wavy long hair, is holding faded out Cueball's hands. The real Cueball is standing to the right, next to his briefcase on the ground. He is holding his hands out towards his kids.] Science Girl: Our new dad never misses our games! Cueball: Nooo!


Birthday

Explanation:
xkcd turns 10 years old on September 30, 2015 (a week after the release of this comic). In this comic Randall honors his webcomic by singing to it the classic " Happy Birthday to You " song.
" Happy Birthday to You " is one of the most commonly sung songs in the English language (and is common in many others). Because of its age, ubiquity and simplicity, it has long surprised people to learn that it was not in the public domain. Warner/Chappell Music claimed the copyright to the lyrics, and has demanded royalties for any recording, publication or public performance for commercial purposes. Total revenues for this song were estimated at US$2 million annually.
This strip refers to a ruling, from the day before the release of this comic, by a federal judge in California ( George King ), stating that the song is not covered by a valid copyright (see Warner's 'Happy Birthday' Copyright Not Valid, Judge Rules ). This ruling resulted from a lawsuit filed by Good Morning To You Productions (singer Rupa Marya and filmmaker Robert Siegel ) against Warner/Chappel Music to declare Warner/Chappel's copyright claim in the song invalid (filing at [1] ). With this ruling, the court declared that Warner/Chappell does not have a copyright claim to the song, and therefore the song can now be sung or published by anyone, in any context, without having to pay royalties to Warner/Chappell.
The ruling does not go so far as to declare the song to be in the public domain, leaving it more correctly defined as an orphan work . Randall seems to be celebrating the fact that this strip, which would have put him at risk for a lawsuit the day before, is now unlikely to be challenged since the odds of a new party appearing and successfully claiming copyright on the lyrics and subsequently demanding license fees is approximately zero.
The title text is a joke that refers to Randall calling the police against Chuck E. Cheese's as well as his own friends and parents when they sang "Happy Birthday" and did not pay royalties. The song is very commonly used in entertainment restaurants, such as Chuck E. Cheese's, and at both grown-ups' and children's birthdays. Because restaurants are commercial enterprises, public performances of the song, prior to this ruling, would potentially have exposed the restaurant to liability claims (though singing it at a private birthday party would not). In either case, calling the police would be an extreme overreaction.
However, many restaurants (for example, Olive Garden ) actually have staff sing a special birthday song (not Happy Birthday To You ) to avoid having to pay royalties.
[Caption above the frame:] xkcd turns 10 years old this month. In light of last night's court ruling in Rupa Marya v. Warner/Chappell Music Inc. , I would just like to say:
[The song text is written, with nine musical notes, three groups on each side of the text, above a birthday cake with 10 lit candles. The cake has two distinct layers. On each layer there are drawn 6 xkcd stick figures with small black bullets between them. The center bullet in the bottom layer is shaped like a heart. The figures at the edges can be difficult to recognize. The figures in the upper layer and from the left are: A man with a hat (hard to see if it is one of the recognized characters), White Hat, Megan, Pony Tail, Hairy and Cueball (hard to see him properly). Similar in the lower layer: Black Hat, Danish, Beret Guy, Rob, Cutie, and a girl (hard to see, but looks like girls hair, not a hat).] Happy birthday to you Happy birthday to you Happy birthday, dear xkcd Happy birthday to you


Picture a Grassy Field

Explanation:
In this comic Megan asks Cueball to picture himself in a grassy field. It is a standard technique to begin a visualization by asking the person to imagine that they are in some calm environment (could be for any kind of meditation / mindfulness like for instance yoga ). A grassy field could have been replaced by a beach at the sea, or a forest with sunbeams coming down through the trees.
Proceeding with the visualization Megan asks Cueball to imagine a creature with the power to be able to escape from any visualized scene, and then tries to convince him that this creature has indeed escaped from his current visualization as it indeed would be able to do. She then proceeds by apologizing for this, but then tells him (warns him) that it from now on might appear in Cueball's daydreams, so he should begin looking out for it. This indicates that she is not at all sorry, but did this intentionally to try and mess with Cueball's head. The idea of the possibility of escaping an imagined situation was already used in 248: Hypotheticals . Now that Megan has introduced both the idea of the creature and the idea that it may appear in his daydreams, Cueball will almost certainly think of it from time to time, creating a self-fulfilling prophecy.
In the title text Megan proposes a solution to get rid of the creature in Cueball's daydream, namely by picturing the only creature that the first fears. However, if this new (maybe quite scary) creature should be able to pursue the original creature, then it would also have to be able to move through visualized scenes just as easily. And this is what Megan pretends happens again. So now the problem is that Cueball has two creatures on the loose in his daydreams. And even if the second scares the first away, he would then still have the new one to worry about.
[Megan and Cueball are walking together.]
Megan: Picture a grassy field. Megan: In the center sits a small, pale, big-eyed creature with the power to escape from any visualized scene and move freely through the brain that imagined it. Megan: It glances around nervously and- Megan: -whoops, where'd it go? Megan: Sorry about that! Keep an eye out for it in your daydreams.


NASA Press Conference

Explanation:
This comic is a reference to the press conference held by NASA on 28th September 2015, (the same day this comic was published), which confirmed the existence of liquid water at the surface of Mars . The comic was posted before the NASA press conference was held, although speculation about the announcement had already occurred.
The "questions" portion of the press conference is derailed by Beret Guy , acting as a reporter for a network known only as "The News". He first comments he is holding a microphone so he is "real loud now." He then asks how the data about Mars relates to data in other fields like medicine and sports. This may seem like an intelligent question upon first glance, but it is in fact nonsensical.  Afterwards he asks if Mars has been "ruined" by getting wet, or if Mars will be okay when it dries out. Some things, e.g. indoor furniture, can be damaged by water, but Mars is not one of those things [ citation needed ] . When asked if he has any other questions he asks why Luke Skywalker was being hassled at the Mos Eisley Cantina in Star Wars . ( Dr. Evazan and Ponda Baba simply told Luke that "[they] don't like [him]", but Beret Guy is evidently not satisfied by that explanation.) Although this may be somewhat space-related, NASA is not an organization that explains films, whether or not they are space related. The other reporters forget their original questions and join in on the irrelevant discussion, much to the dismay of the NASA scientist.
This is probably meant to mock previous NASA press conferences, where reporters have asked inane questions that reveal their total ignorance of the field.
The title text refers to Elon Musk , who suggested nuking Mars as a faster way of warming it up to make it habitable.
[Cueball is standing behind a lectern with the NASA logo on it.] Cueball: That concludes the press conference. Any questions? Cueball: Yes, you, from... it just says "The News"?
[Beret Guy is standing in a crowd holding a microphone.] Beret Guy: Hi! I have a microphone so I'm real loud now. Beret Guy: How does this Mars data compare to data from other fields? Like medicine? Or sports?
Cueball (offscreen): That question makes no sense. Beret Guy: If there's water on Mars, is it ruined? Beret Guy: Or will it be okay when it dries out? Cueball (offscreen): Any other questions?
[The shot zooms out, showing that Cueball and the lectern is standing on a podium and also the crowd comes in to view.] Beret Guy: What were those guys hassling Luke in the Mos Eisley Cantina trying to accomplish? I felt like I was supposed to understand that. Cueball: Anyone else? Ponytail: That's now my question, too. Megan: Were they just picking a fight? Ponytail: If so, why did...


Moments of Inspiration

Explanation:
Isaac Newton 's original examples describing the force of gravity show an apple falling from a tree in order to explain why the apple falls toward the Earth, instead of the Earth falling toward the apple. He is often said to have been inspired by watching falling apples ; in common folklore, this developed into the legend that he was actually struck by an apple. The first part of this comic retells that famous legend. The later panels depict similar (but more and more implausible) legends that could emerge if we were to assume that other scientists' most famous examples and discoveries were based on actually observing some mundane everyday event taking place.
In the first situation, we not only see the apple fall on Newton's head, we also see the Moon. This was one of the first astronomical objects on which he used his theory of gravity. He calculated its orbit around the Earth and found that it fit with the theory.
In the second situation, Cueball throws a baseball towards Lise Meitner , but when she fails to catch the ball it hits one of her porcelain model-atoms. In this way, Meitner discovered a way to split the atom. Cueball may represent Otto Hahn , since they were part of the Hahn-Meitner-Strassmann team that worked on this problem. Hahn was later awarded the Nobel Prize for Chemistry, where Meitner was overlooked. Throwing something at someone and asking them to think fast is a common "joke", where the receiver rarely has a chance to actually catch the object. But in this case, it could also be a reference to the fact that she then thought fast then made a major discovery. Or if it is Hahn, then he thought faster and got the award instead of her. The porcelain models might also be a reference to Meissen porcelain , in German called "Meißner Porzellan", where "Meißner" is phonetically very similar to "Meitner". Meitner has previously been mentioned in the comic 896: Marie Curie , which more or less explains why Randall did not choose the more famous Marie Curie as the female example in this comic. Meitner is not very well known in the public, compared to the three men or Curie, but this may exactly be the point for choosing her. She should have been just as famous considering what splitting the atom has led to . Also, there's not much in Marie's story that could be put down to fanciful anecdotes. "All" she did was extract a few chemicals and study their properties.
In the third situation, it is indicated that half of Charles Darwin 's children had beaks , a property not normally found in human children. [ citation needed ] This would make it very difficult for them to drink soda from a glass or through a straw, compared to his normal children with mouths. Based on this observation he developed his ideas about natural selection and evolution . The comic is unclear on whether this makes them more or less fit to survive and reproduce. This is a reference to Darwin's initial findings on the HMS Beagle on how Galapagos finches with differently shaped beaks are better suited for specific types of food and therefore are better selected for in environments where those foods are available. The title text furthers this, see below. Darwin later in life feared that, having married his cousin, their consanguinity would increase the risk that his children would be born with birth defects (although he did not fear that they would be born with beaks). The difficulty caused by beaks when drinking liquids could be a reference to the Aesop's fable The Fox and the Stork .
In the fourth situation Albert Einstein remarks to a man that it's annoying that the man's twin brother keeps flashing a light from a train when Einstein is trying to check his clock. He then comes to a sudden revelation. This references several of Einstein's (different — they make little sense together in this manner) thought experiments on special relativity , such as the twin paradox (the twin on the train should be younger after decelerating to a stop), a clock built from a beam of light, the time dilation experienced by the observer in the moving frame of reference , and the various constructs involving trains and light(ning) flashes used to illustrate the relativity of simultaneity .
The title text shows that beaks rather than mouths are more useful for eating foods that have shells that need to be cracked open before eating like nuts and seeds. Here it is clear that in the John and Mildred family you starve if you cannot eat such foods, and thus it's an advantage for survival to have a beak instead of a normal mouth. "John" and "Mildred" may be Mildred and John T. Scopes of the famous 1925 " monkey trial " in which John was fined $100 for teaching evolution in a Tennessee school.
[Isaac Newton, with curly long hair, sits under a tree. A waning crescent moon can be seen. An apple falls and hits him on the head. There is a caption in a frame that breaks the top border of the main frame:] Isaac Newton Apple falling: Bonk Isaac Newton: Ow!
[Isaac Newton rubs his sore head.] Isaac Newton: Aha!
[Cueball throws a baseball towards Lise Meitner with short dark hair. (The ball can be seen in the next frame). She turns towards him too late to react and completely fails to even try catching the ball. There is a caption in a frame that breaks the top border of the main frame:] Lise Meitner Cueball: Hey Lise! Think fast! Ball hitting something (off-screen): Crash
[Lise takes her hands to her mouth and she watches the broken porcelain atom lying in two pieces on the floor where it has fallen off a desk. On the desk, three other intact atoms can be seen. The baseball lies behind her.] Lise Meitner: Oh no! My collection of porcelain atoms! Lise Meitner:...Hmm.
[Four kids are standing in front of Megan and Charles Darwin (with a big beard and hair behind the ears). All the kids are trying to drink a glass of soda with a straw in them. The first kid is a boy with dark flat hair and sips soda through the straw with his mouth. The next kid is a boy with standing black hair, he tries in vain to drink with his beak open on each side of the glass. The third kid is a girl with her hair in a bun. She tries to get her beak into the glass which she has put on the floor. The last kid is a boy version of Cueball who slurps his soda through the straw. There is a caption in a frame that breaks the top border of the main frame:] Charles Darwin Megan: I gave our kids soda, but the ones with beaks always have trouble drinking it. Charles Darwin: I've noticed that... Boy with flat dark hair: Sip sip Boy with standing black hair and a beak: Crunch Girl with her hair in a bun and a beak: Peck peck Cueball like kid: Sluurp
[A hairy guy is standing in front of Albert Einstein (with wild hair and a mustache), who is holding one hand to his head and has a clock in his other hand. Behind them is a train, with a locomotive at the front and a wagon behind that stretches beyond the frame. Another hairy guy has his head out of the front window of the wagon and is flashing a light towards the other two. In the next three windows can be seen passengers, two with Cueball like heads and one with hair. There is a caption in a frame that breaks the top border of the main frame:] Albert Einstein Albert Einstein: I wish your twin brother would stop shining lights at us from that train. I can barely see my clock! Albert Einstein: ...Wait!
This comic appeared on xkcd's ten-year anniversary.


Similarities

Explanation:
There's a common punchline in which the plot lines of two thematically-different works of fiction (usually movies) are compared in greatly-abbreviated form, and the speaker sarcastically concludes that the two movies are "basically the same". For sake of example, Disney's Aladdin and James Cameron 's Titanic both feature a story in which a lower-class boy and an upper-class girl fall for each other, among other cherry-picked yet interesting parallels. But due to the different emotional tones of the films (a family-friendly "happy ever after" tale and a disaster thriller respectively), one would not normally describe them as similar.
This comic spoofs the idea. Instead of comparing plot lines of two movies, Ponytail and Cueball compare the respective movies' development histories.
The Martian was originally a serialized story written by Andy Weir on his blog which was later compiled into an ebook for people to easily download, then published into a physical book, and has now had a movie created based on it. The movie was officially released in the US on the same day this comic was released (October 2, 2015).
Fifty Shades of Grey began as a fan fiction of a well known brand (the Twilight book series ). It was originally written on the internet by E. L. James . It was then transformed into a successful book series which was later turned into a movie released in February 2015. The book was already referenced back in 2012 in 1128: Fifty Shades .
Since Fifty Shades is a romance story about a sadomasochistic relationship, and The Martian is a very technical story about surviving completely alone on a hostile planet, the two books could not be any more different, hence the joke due to the juxtaposition.
Cueball continues the joke by joining the two titles using red for Mars, to make a new book title, that should cover both books: Fifty Shades of Red. Ponytail says to Cueball that such a book would be irresistible for him. She does this by daring him to say that he wouldn't read it, believing he could not say so without lying. The red could also be a reference to the safe word used in the Fifty Shades series, for when things hurt instead of being pleasing. It means stop! But stop should be a word you can say, without the other one stopping, adding to the illusion of being forced; actually stopping would be done by saying red . Reading it like that, the title would be Fifty Shades of Stop !
It is not clear from the comic if Randall liked the movie. Since he now compares it to a book series that has been described as mommy porn it could indicate that he was not so satisfied with the movie. On the other hand, he may just have noticed this connection and found that it would make a great joke here on the release day.
An alternative explanation is that Randall is commenting on the frequent comparisons made between The Martian and the movie Interstellar , comparisons centering on the fact that in both Matt Damon plays an astronaut stuck on a deserted planet, but also mentioning, among others, the appearance of Jessica Chastain and the similar design of the spacesuits used in both movies. These comparisons have been prevalent on the Internet long before the release of The Martian, so evidently spurred by the movie trailers, rather than by reviews of viewers. Randall is making the point that to one who has seen the movie, comparing The Martian to Interstellar is as far-fetched as comparing it to Fifty Shades of Grey. According to this interpretation, Randall is not ridiculing The Martian, but rather Interstellar. By proxy, he is praising The Martian. Given that Randall has chosen (now for the second time) to mention the film explicitly on his site, the idea that he is promoting The Martian is perhaps more plausible than the idea that he is expressing dissatisfaction with it. The title text, where he makes a similar comparison, favoring The Martian over Star Wars: The Force Awakens, further boosts this explanation.
It is possible that the brand that The Martian derives from is NASA itself. The Martian has been compared to the film Apollo 13 by Randall in 1536: The Martian . Apollo 13 does indeed glorify the roles of the NASA engineers, and The Martian does a similar thing. That Randall would go see this movie as soon as it was released was already made perfectly clear back in June when he released the comic 1536: The Martian showing how excited he is about the book. He then really looked forward to the movie.
Randall indicates in the title text that he has just seen the movie (certainly possible, if he caught a midnight screening; perhaps he drew this comic in advance and wrote the title text after) and finds the Sojourner rover adorable. Of course, he could also have seen it in the trailers.
The BB-8 mentioned in the title text is the astromech droid from the movie Star Wars: The Force Awakens and is available as a toy (see also BB-8 on the official Star Wars home page). Sojourner was the Mars Pathfinder robotic rover used by Mark Watney, the protagonist of The Martian (played by Matt Damon in the movie), to allow him to contact Earth. Randall indicated that he thinks the Sojourner is much cuter than BB-8, and that he would like to have one as a pet. He then states that the Sojourner has always been the cutest among all the Mars rovers . The cuteness of Mars Rovers is also mentioned in 2433: Mars Rovers . There have been four so far the other three being Opportunity , Spirit and Curiosity which have already been used in xkcd comics: 695: Spirit , 1091: Curiosity and 1504: Opportunity .
[Ponytail is talking to Cueball.]
Ponytail: So it's a work of fiction about a well-known brand. written on the Internet by an enthusiast, republished as a bestselling book, and then made into a big movie. Cueball: Yup.
[Ponytail holds her hand to her chin. Beat panel.]
[Ponytail is talking to Cueball again.] Ponytail: Yeah, The Martian and Fifty Shades of Grey are basically the same book. Cueball: " Fifty Shades of Red? " Ponytail: Man, tell me you wouldn't read that.


Keyboard Problems

Explanation:
This comic parodies how people diagnose and solve computer problems . Cueball and Megan are trying to solve a keyboard issue, but are somewhat incompetent at diagnosing the issue. Cueball in particular blames a broken keyboard on software or a keyboard virus .
In the comic, Cueball complains that some keys in his keyboard don't work. Generally speaking, this could be due either to a software problem (e.g. the keyboard driver not working properly, or some program ignoring keypresses) or to a hardware problem (the keyboard is physically damaged, e.g. because of dirt under the keys).
If the problem is in the software, booting from a different operating system (e.g. an external recovery disk) should solve it, as the computer would no longer be using the faulty software. However, if the problem is in the hardware, changing the keyboard should solve the problem as the new keyboard would no longer be physically damaged (and would have no dirt under the keys).
However, the problem stays there after booting from an external recovery disk (so it's not a software problem) and it has "followed Cueball since his last computer," (i.e. the problem persists after changing to a new laptop with a new keyboard, so it's not a hardware problem). Cueball is (reasonably) puzzled.
Megan seems to be used to Cueball's computer behaving strangely, and she doesn't even attempt to explain or solve the problem. The only explanation she needs for the problem is that "it's Cueball's computer." The characters in this comic are probably the same as in 1084: Server Problem , 1316: Inexplicable , and 349: Success .
The last panel is a reference to The Terminator , a 1984 movie often referenced in xkcd. In the movie, the artificial intelligence named Skynet initiates a nuclear war, destroying most of humanity, then sends killing machines to finish the rest. These include flying drones — Megan suggests that if such robots come to Cueball's vicinity, they will (physically) crash since computers around Cueball can't seem to ever work properly, and so hiding in Cueball's house she should be safe from the robots.
The title text refers to main plot of the movie and its sequel Terminator 2: Judgment Day . As Skynet's army is losing the battle against the human Resistance movement, it finds a way to send a humanoid robot T-800 back in time to kill the mother of the Resistance's leader. The Resistance in turn sends Kyle Reese back in time to protect her. In the sequel, the situation repeats with the more advanced T-1000 being the killer and a reprogrammed T-800 being the protector of the child (the future leader). Along the way, they manage to destroy the research lab where Skynet hardware is to be born in the future. The title text suggests an alternative mission into the past, sending Cueball back in time and using his power to cause Skynet to terminally malfunction instead of destroying it physically (as Skynet was created later anyway, despite the destruction of the research lab).
[Cueball sits between two laptops. Megan stands behind him.]
Cueball: Keys on my keyboard keep failing, even when I boot from an external recovery disk. Megan: Sounds like it's hardware, then.
[Cueball moves over to the laptop behind him.]
Cueball: Yeah... except the problem followed me from my last computer. Megan: You have the most bizarre tech issues.
[Cueball picks up the keyboard from the rear computer and plugs it into the one in front of him.]
Cueball: It must be spreading via keyboards. This one won't work with any computer now. Megan: When the robot apocalypse happens, I'm hiding out in your house. Any Skynet drones that come near will develop inexplicable firmware problems and crash.


Food Rule

Explanation:
There are various vegetarian diets which restrict certain foods for ethical or personal concerns. Real vegetarians do not eat any kind of meat, but some only refrain from eating red meat, although this means they are not true vegetarians. Vegetarianism can go as far as to not eating (or even using) any kind of products coming from an animal (i.e. veganism ). The comic is a joke on one of the vegetarian rules, namely don't eat anything with a face . This rule is difficult to follow, because it is subjective whether people think a given animal has a face , causing disagreement about what is allowed and what is forbidden to eat.
Randall presents a list (see details below) of allowed and forbidden food in his diet. For example, he eats meat from typical-looking animals like beef, pork, chicken, and fish. He will also eat plants like fruit, vegetables and grain. But he refuses to eat some of the more odd-looking creatures from the sea like squids, shrimps and oysters. Below the list he explains his rule for what can be eaten: I won't eat something if I have to Google to figure out whether or not it has a face , which is a joke on the disagreements about the don't eat anything with a face rule. The joke is particularly teasing as it allows most (if not all) kinds of meat, which are the most strictly forbidden foods for even the mildest of vegetarians. Randall does not care about food having faces, he is worried apparently only about having to defend the position that some particular food has a face or not. While it's clear, at least to Randall, that a cow has a face and an apple does not, some beings are harder to classify into one of these categories. For Randall this goes for shrimps, oysters and squids; and apparently actual vegetarians also struggle with these creatures, as can be seen in several on-line questions ( 1 ).
The title text gives another rule that also would make these same three omissions. This rule is about not eating invertebrates (animals without a vertebral column , i.e. spineless creatures). As the first four items on the list are meat from four different animals of the type vertebrates (with vertebral column) and the last three items are from plants , that explains why these are all OK to eat. But the middle three items are three different animals of the type invertebrates, which Randall does not eat.
Randall's reason for avoiding invertebrates is somewhat outlandish: he fears that the spirits from creatures he has eaten will come back to haunt him. In horror movies, as well as in video games and roleplaying games with fantastic elements, undead creatures often appear as spooky skeletons (i.e. the Stalfos of the Legend of Zelda ); however invertebrates have no skeleton so Randall can't figure out what kind of spooky undead creature will come after him if he eats them (invertebrates may have a shell or another type of exoskeleton , but these do not look at all like the typical mental image of a skeleton). Randall imagines that he'll be able to fight a typical skeleton, but is afraid of the unknown ghostly creature an invertebrate may become after dying.
The comic may also be a joke on the modern paleo diet trend, which emphasizes eating fruit, vegetables, and meat ("anything with a face").
Randall has previously depicted cuttlefish as spooky in 520: Cuttlefish , and he's also mentioned his dislike of certain foods (namely lobster - another invertebrate) in 1268: Alternate Universe .
Here is a list with explanation for each item on Randalls food list:
[There is a caption above a list of food with indication whether it is OK or not to eat. Below is another caption.]
My food rule:
Red meat ✓ Pork ✓ Poultry ✓ Fish ✓ Shrimp X Oysters X Squid X Fruit ✓ Vegetables ✓ Grains ✓
I won't eat something if I have to Google to figure out whether or not it has a face.