Booby trap A booby trap is a device or setup that is intended to kill , harm or surprise a person , unknowingly triggered by the presence or actions of the victim . As the word " trap " implies , they often have some form of bait designed to lure the victim towards it . However , in other cases the device is placed on busy roads or is triggered when the victim performs some type of everyday action e . g . opening a door , picking something up or switching something on . Booby traps should not be confused with mantrap s which are designed to catch a person . Lethal booby traps are often used in warfare , particularly guerrilla warfare , and traps designed to cause injury or pain are also sometimes used by criminals wanting to protect drugs or other illicit property , and by some owners of legal property who wish to protect it from theft . Booby traps which merely cause discomfort or embarrassment are a popular form of practical joke . Etymology . The Spanish word bobo translates to stupid , daft , naive , simple , fool , idiot , clown , funny man , one who is easily cheated and similar pejorative terms . The slang of bobo , bubie , translates to dunce . Variations of this word exist in other languages ( such as Latin ) , with their meaning being " to stammer " . Thus , the term " booby trap " gives rise to the idea that an individual with the misfortune to be caught in the trap does so because the individual is a " booby " , or that an individual who is caught in the trap thereby becomes a " booby " . The word has also been applied to the Sula genus of sea birds , with their common name being boobies . These birds , adapted for sea flight and swimming , have large flat feet and wide wingspans , making it difficult for them to run or take flight quickly . As a result , they are considered clumsy and easy to catch when onshore . They are also known for landing aboard seagoing vessels , whereupon they have been eaten by the crew . In approximately 1590 , the word began appearing in the English language as booby , meaning " stupid person , slow bird " . The phrase booby trap originally applied to schoolboy pranks , but took on its more sinister connotation during World War I . Military booby traps . A military booby trap may be used to give away the location of an enemy by triggering a signalling device , or it may be designed to kill or injure a person who activates the trap . Most , but not all , military booby traps involve explosives . There is no clear division between a booby trap and conventional , mass - produced land mine s which are usually hidden under soil , but may be triggered by a tripwire or directional mine designed specifically to work with a tripwire . Other , similar devices include spring - gun s and related mechanisms such as the SM - 70 directional antipersonnel mine . What distinguishes a booby trap is that it is contrived to work in an unexpected manner that takes advantage of the victim ' s ignorance of the mode of operation . It naturally follows that booby trap designs must be many and varied , and for this reason the traps are often at least partially improvised from some item of ordnance , such as an artillery shell , grenade , or quantity of high explosives . However , some mines have features specifically designed for incorporation into booby traps and armies have been equipped with a variety of mass - produced triggering mechanisms intended to be incorporated into booby traps in a wide variety of ways . A booby trap is generally concealed or disguised in some way so that it either cannot be seen or looks harmless . Typically , a booby trap will be hidden inside , behind or underneath another object . Part of the skill in placing booby traps lies in exploiting natural human behaviors such as habit , self - preservation , curiosity or acquisitiveness . A common trick is to provide victims with a simple solution to a problem , for example , leaving only one door open in an otherwise secure building , thereby luring them straight toward the firing mechanism . An example that exploits an instinct for self - preservation was used in the Vietnam War . Spikes known as Punji stick s were hidden in a grassy area . When fired upon , passing soldiers unknowingly take cover in the booby trapped area , throwing themselves down on the spikes . Attractive or interesting objects are frequently used as bait in order to lure victims into triggering the booby trap . For example , troops could leave behind empty beer bottles and a sealed wooden packing case with " Scotch Whisky " marked on it before leaving an area . The rubble - filled packing case might be resting on top of an M5 or M142 firing device , connected to some blocks of TNT or to some C4 explosive stuffed into the empty fuze pocket of a mortar shell . Alternatively , the weight of the packing case might simply be holding down the arming lever of an RGD - 5 grenade with a zero - delay fuze fitted and the pin removed . Either way , when the case is moved ; the booby trap detonate s , killing or severely injuring anyone in the immediate area . Many different types of bait object can be used e . g . soldiers will be tempted to kick an empty beverage can lying on the ground as they walk past it . However , the beer can ( partially filled with sand to add weight ) may be resting on top of an M5 pressure - release firing device screwed into a buried M26 grenade . Many purpose - built booby - trap firing devices exist such as the highly versatile M142 universal firing device ( identical to the British L5A1 or Australian F1A1 ) , or Yugoslavian UMNOP - 1 which allow a variety of different ways of triggering explosives e . g . via trip wire ( either pulling it or releasing the tension on it ) , direct pressure on an object ( e . g . standing on it ) , or pressure release ( lift / shift something ) etc . Almost any item can be booby - trapped in some way . For example , booby trapping a flashlight is a classic tactic : a flashlight already contains most of the required components . First of all , the flashlight acts as bait , tempting the victim to pick it up . More importantly , it is easy to conceal a detonator , some explosives , and batteries inside the flashlight casing . A simple electrical circuit is connected to the on / off switch . When the victim attempts to turn the flashlight on to see if it works , the resulting explosion blows their hand or arm off and possibly blinds them . The only limits to the intricacy of booby - traps are the skill and inventiveness of the people placing them . For example , the " bait object " ( e . g . a cash box in a corner of the room ) which lures victims into the trap may not in fact be booby - trapped at all . However , the furniture which must be pushed away in order to get to the bait has a wire attached , with an M142 firing device connected to a 155mm artillery shell on the other end of it . A booby trap may be of any size . However , as a general rule the size of most explosive booby traps use between 250 g and 1 kg of explosive . Since most booby traps are rigged to detonate within a metre of the victim ' s body , this is adequate to kill or severely wound . As a rule , booby - traps are planted in any situation where there is a strong likelihood of them being encountered and triggered by the targeted victims . Typically , they are planted in places that people are naturally attracted to or are forced to use . The list of likely placement areas includes : A booby trap does not necessarily incorporate explosives in its construction . Examples include the punji sticks mentioned above and deadfall trap s which employ heavy objects set up to fall on and crush whoever disturbs the trigger mechanism . However , setting non - explosive booby traps is labour - intensive and time - consuming , they are harder to conceal and they are less likely to do serious damage . In contrast , booby traps containing explosives are much more destructive : they will either kill their victims or severely wound them . Effects . In addition to the obvious ability of booby traps to kill or injure , their presence has other effects . These include the ability to : Booby traps are indiscriminate weapons ; like anti - personnel mine s they can harm civilians and other non - combatants ( during and after the conflict ) who are unaware of their presence . Therefore , it is vitally important for any force which places booby traps to keep an accurate record of their location so they can be cleared when the conflict is over . Usage throughout history . A type of booby - trap was referred to in an 1839 news story in " The Times " . During the Vietnam War , motorcycles were rigged with explosives by the National Liberation Front and abandoned . U . S . soldiers would be tempted to ride the motorcycle and thus trigger the explosives . In addition , NLF soldiers would rig rubber band grenades and place them in huts that US soldiers would likely burn . Another popular booby trap was the " Grenade in a Can " , a grenade with the safety pin removed in a container and a string attached , sometimes with the grenade ' s fuse mechanism modified to give a much shorter delay than the four to seven seconds typical with grenade fuses . The NLF soldiers primarily used these on doors and attached them to tripwires on jungle paths . The CIA and Green Berets countered by booby - trapping the enemy ' s ammunition supplies , in an operation code - named " Project Eldest Son . " The propellant in a rifle or machine - gun cartridge was replaced with high explosive . Upon being fired , the sabotaged round would destroy the gun and kill or injure the shooter . Mortar shells were similarly rigged to explode when dropped down the tube , instead of launching properly . This ammunition was then carefully re - packed to eliminate any evidence of tampering , and planted in enemy munitions dumps by covert insertion teams . A sabotaged round might also be planted in a rifle magazine or machine - gun belt and left on the body of a dead NLF soldier , in anticipation that the deceased ' s ammo would be picked up and used by his comrades . No more than one sabotaged round would be planted in any case , magazine , or belt of ammunition , to reduce the chances of the enemy finding it no matter how diligently they inspected their supplies . False rumors and forged documents were circulated to make it appear that the Communist Chinese were supplying the NLF with defective weapons and ammunition . Northern Ireland . During the " Troubles " in Northern Ireland , booby trap bombs were often used by the Provisional Irish Republican Army ( IRA ) to kill British Army soldiers and Royal Ulster Constabulary officers . A common method was attaching the bomb to a vehicle so that starting or driving it would detonate the explosive . According to the Sutton Index of Deaths , 180 deaths during the Troubles were the result of booby trap bombs , the vast majority of them laid by the Provisional IRA . Middle East . During the Al - Aqsa Intifada , some Arab - Palestinian groups made wide use of booby traps . The largest use of booby traps ( between 2000 – 2005 , the period of the Intifada ) was in the Battle of Jenin during Operation Defensive Shield where a large number ( 1000 - 2000 according to Palestinian militant captured in Jenin during the battle ) of explosive devices were planted by insurgents . Booby traps had been laid in the streets of both the camp and the town , ready to be triggered if a foot snagged a tripwire or a vehicle rolled over a mine . Some of the bombs were huge , containing as much as 250 lb ( 110 kg ) of explosives . To counter the booby traps , anti - tank and anti - personnel mines the IDF sent armored D9 bulldozers to clear the area out of any explosive device and booby trap planted . The IDF D9 bulldozers were heavily armor ed and thus did not sustain any damage from the explosions , which were triggered by them as they pushed forwards . Eventually , a dozen D9 bulldozers went into action , razing the center of the refugee camp and forcing the Palestinian militants inside to surrender . Gallery . As a rule , most purpose - made military booby - trap firing devices contain some form of spring - loaded firing pin designed to strike a percussion cap connected to a detonator at one end . The detonator is inserted into an explosive charge e . g . C4 or a block of TNT . Triggering the booby - trap ( e . g . by pulling on a trip - wire ) releases the cocked firing pin which flips forward to strike the percussion cap , firing both it and the attached detonator . The resulting shock - wave from the detonator sets off the main explosive charge . Criminal and security use . Booby traps can also be applied as defensive weapons against unwelcome guests or against non - military trespassers , and some people set up traps in their homes to keep people from entering . Laws vary : the creator of the trap may be immune from prosecution since the victim is trespassing , or the home owner may be held liable for injuries caused to the trespasser . Computer viruses . Many computer viruses take the form of booby traps in that they are triggered when an unsuspecting user performs an apparently ordinary action such as opening an email attachment . Practical jokes . Instead of being used to kill , maim and injure , booby traps can also be used for entertainment . Practical joke booby traps are typically disguised as everyday items such as cigars or packets of chewing gum , nuts or other snack items . When the victims attempts to use the item , the trap is triggered . Two of the best known examples of this are the exploding cigar and dribble glass ; others include the Snake Nut Can and shocking gum . Booby traps can also be constructed out of household or workplace items and be triggered when the victim performs a common action . Examples of this include loosening the bolts in a chair so that it collapses when sat on , or placing a bucket of water on top of a partly open door so that when the door is fully opened , the bucket tips onto the victim . A variant is the water bucket which when " thrown " at the target , is full of confetti .