Question: Which episode of "Rick and Morty"  aired unannounced on April 1, 2017 and was replayed every half hour from 8pm to 12am ET, as part of Adult Swim's annual April Fools' prank?

Context articles: Meeseeks and Destroy
Rabbot
WSYY-FM
Lawnmower Dog
April Fools' Day
Hyper Text Coffee Pot Control Protocol
Great Blue Hill eruption prank
The Rickshank Rickdemption
Rick and Morty (season 3)
List of The Brak Show episodes

"Meeseeks and Destroy" is the fifth episode of the first season of "Rick and Morty".
 It premiered on Adult Swim on January 20, 2014.
 The episode was written by Ryan Ridley and directed by Bryan Newton.
 In the episode, Rick provides the family with a solution to their problems, freeing him up to go on an adventure led by Morty.
 The episode has been well received, and was seen by about 1.6 million viewers when it was first aired on the Adult Swim channel.
"Rabbot" is the pilot episode and the first episode of the first season of the animated television series "Aqua Teen Hunger Force".
 A rough-cut version of this episode originally aired in the United States prior to the launch of Adult Swim on December 30, 2000 on Cartoon Network unannounced, the final cut of this episode later aired on Adult Swim on September 16, 2001.
 In the episode Master Shake, Frylock, and Meatwad investigate the recent destruction of Carl's car, while a giant mechanical rabbit destroys downtown.
WSYY-FM (94.9 FM) is a radio station broadcasting for approximately 18¼ hours per day, 7 days a week (from 4:55AM through 11:10PM ET) under the slogan, ""Radio With An Attitude"".
 Playing a mix of oldies/classic hits, adult contemporary, rock music, and some country crossovers, the station broadcasts an Adult Hits/Full-Service format for approximately 16 hours per day, from 6:00AM through 10:00PM ET (reserving the first and, also, the final hour of their broadcast day to "When Radio Was").
 "The Mountain 94.9" carries local high school sports in season.
 "The Mountain 94.9" had also carried the complete schedule of Red Sox Baseball (from 1997 through 2015, prior to becoming a Former Affiliate in 2016, which was when Millinocket's affiliation with the Red Sox Baseball would ultimately be transferred over to co-owned WSYY-AM, thus concluding the frequent interruptions to the music on "The Mountain 94.9" during Baseball season).
 The station currently features programming from CBS Radio and carries CBS Radio News at the top of every hour (and has been an affiliate of that network for many decades).
 Licensed to Millinocket, Maine, United States, the station's broadcast signal serves the Central Penobscot County, Eastern Piscataquis County, and Southern Aroostook County Maine areas, and the station is licensed to serve the town of Millinocket, Maine, the very town where its studios/offices and tower site are located.
 The station is currently owned by Katahdin Communications, Inc.
 WSYY-FM originally went on the air in 1978 on 97.7 FM as WKTR, upgrading to its current facilities in 1984 on 94.9.
 Prior to their "The Mountain 94.9" branding, WSYY-FM used to be referred to as "North Country 95", airing a full-time Country Music format.
 The current format, branding, and slogan was probably adopted around March 1, 2004, when Katahdin Communications, Inc. assumed control of WSYY-FM & WSYY-AM from Katahdin Timberlands, LLC (as a result of the radio station facing increasing land disputes), initially as a short term lease agreement but the transfer of ownership ultimately became permanent.
 Those same land disputes would eventually lead to a loss of WSYY-FM's 23,500 watt transmitter location (featuring an antenna HAAT of 211 meters); as a result, WSYY-FM may have been operating under a Special Temporary Authority License (a 12,000 watt facility with an antenna HAAT of 68 meters via Hammond Ridge on Lake Road, about two miles from Millinocket Municipal Airport), ever since as long ago as late 2007, pending a planned permanent move to a 22,000 watt facility with an antenna HAAT of 198.4 meters (from just off Nicatou Road in Medway, well east of WSYY-FM's old or current transmitter tower location).
 On November 23th, 2016, the CP for this proposed move was modified to a 45,000 watt facility with an antenna HAAT of 146.7 meters, the first time this proposed move has ever received official approval from the FCC.
 WSYY-FM is one of the two Maine affiliates—apart from WLOB—of When Radio Was (7 days a week from 5:00AM through 6:00AM ET and also from 10:00PM through 11:00PM ET), is one of the two Maine affiliates (WWMJ) of The Acoustic Storm (Saturdays from 9:00AM through 12:00PM ET), is Maine's only affiliate of the Crook & Chase syndicated Country Music countdown programming (Sunday afternoons from 2:00PM through 6:00PM ET), and is an affiliate of the Blues Deluxe radio show.
 WSYY-FM/WSYY-AM are unusual in that while these stations are authorized to broadcast 24 hours a day, the stations both have sign-offs every day (WSYY-AM signing off at sun-down, broadcasting only on Weekends (but not between Monday-through-Friday) and WSYY-FM broadcasting for approximately 18¼ hours per day, 7 days a week, WSYY-FM's broadcast day concluding with the 11:00PM ET Top-of-the-Hour CBS Radio newscast and then a Nightly Sign-Off Announcement and then an instrumentation of the American national anthem, followed by Dead Air amidst a Transmitter Power-Down, not Signing Back Onto The Air until 4:55AM ET).
 In Old Town and also Bangor (and continuing southward and/or southwestward), the station has strong FM co-channel interference with Portland-market WHOM (which transmits from atop Mount Washington in New Hampshire, the tallest peak in the Northeast and had for a long time claimed on its website that it has the largest coverage area of any FM station in the United States, its signal spanning five states: NH, ME, VT, MA, NY and also parts of Southern Quebec Province, Canada), this matter being especially problematic before dawn or after dusk.
 In favorable atmospheric conditions, a very weak signal of WHOM can be DX-ed in Millinocket during overnight hours (when WSYY-FM is off-the-air).
"Lawnmower Dog" is the second episode of "Rick and Morty".
 It premiered on Adult Swim on December 9, 2013, was written by Ryan Ridley, and directed by John Rice.
 In the episode, Rick gives Jerry a device to enhance the dog's intelligence, whilst Rick and Morty get lost in the dreams of Morty's math teacher.
 The episode was well received, with approximately 1.5 million viewers when airing.
April Fools' Day (sometimes called All Fools' Day) is celebrated every year on April 1 by playing practical jokes and spreading hoaxes.
 The jokes and their victims are called April fools.
 People playing April Fool jokes expose their prank by shouting April Fool.
 Some newspapers, magazines, and other published media report fake stories, which are usually explained the next day or below the news section in small letters.
 Although popular since the 19th century, the day is not a public holiday in any country.
The Hyper Text Coffee Pot Control Protocol (HTCPCP) is a facetious communications protocol for controlling, monitoring, and diagnosing coffee pots.
 It is specified in RFC 2324, published on 1 April 1998 as an April Fools' Day RFC, as part of an April Fools prank.
 An extension, HTCPCP-TEA, was published as RFC 7168 on 1 April 2014 to support brewing teas, which is also an April Fools' Day RFC.
On April 1, 1980, WNAC-TV aired a fake news bulletin that stated that Great Blue Hill was erupting.
 Intended as an April Fools joke, the prank resulted in panic in Milton, Massachusetts and the surrounding area.
"The Rickshank Rickdemption" is the first episode in the third season of the American animated television sitcom "Rick and Morty", and the twenty-second episode overall in the series.
 It was written by Mike McMahan and directed by Juan Meza-Leon.
 The season three premiere first aired unannounced on Adult Swim in the United States on April 1, 2017 when it was watched by 676,000 American households.
 On the first day of its original broadcast, "The Rickshank Rickdemption" was replayed every half hour from 8pm to 12am ET with improved ratings, as a part of Adult Swim's annual April Fools' Day joke.
The third season of the animated television series "Rick and Morty" originally aired in the United States on Cartoon Network's late night programming block, Adult Swim.
 It premiered with "The Rickshank Rickdemption," which aired unannounced on April 1, 2017 and was replayed every half hour from 8pm to 12am ET, as part of Adult Swim's annual April Fools' prank.
 The episode was also simulcast as a looping live stream on Adult Swim's site.
 The remaining episodes began airing on July 30, 2017.
 The season will feature a total of 10 episodes.
This is a list of episodes for the animated Adult Swim television series, "The Brak Show".
 The pilot episode, "Mr. Bawk Ba Gawk", aired unannounced on December 21, 2000, on Cartoon Network.
 The series officially premiered with "Goldfish" on September 2, 2001, on Adult Swim, and ended with three seasons and 28 episodes on December 31, 2003, with "Cardburkey".
 On May 24, 2007, an additional webisode entitled "Space Adventure" was released on Adult Swim Video, no further webisodes have ever been produced.