Ever since it expanded from airing two to six days a week in 2003 (it became a nightly block the following year), Adult Swim has always had fun with its April Fools broadcasts. Some years that means editing the night's regular programming with farts or mustaches, while other years that means shifting up the line-up entirely with something weird or unexpected.
The following five April Fools pranks stand out as some of the funniest, cleverest and/or most genuinely awesome moments in the adult animation/comedy network's history.
5. Adult Swim Jr. (2021)
This year's Adult Swim April Fools prank is one of the funniest ones in concept, even if it couldn't quite live up to its full promise. At midnight, Adult Swim became the pre-school block "Adult Swim Jr." Episodes of Rick and Morty and Aqua Teen Hunger Force (now called Rick and Morty Babies and Aqua Child Hunger Force) were redubbed with child voice actors and new theme songs, while commercials promised other kid-friendly spin-offs like Superjuvie and The Venture Nephews.
Alas, the scale of this prank was much smaller than pranks from previous years. Only two episodes got redubbed and were shown twice; by 1:30 AM, it was back to Adult Swim's regularly scheduled programming. This may be due to the challenges of pulling together these pranks during the COVID-19 pandemic as well as budget cuts across the board at WarnerMedia companies.
4. Aqua Teen Movie "Premiere" (2007)
2007 was the first year Adult Swim did not one, but two pranks for April Fools. The first prank, editing a marathon of Perfect Hair Forever to make it look like an old VHS anime fansub, was cute enough, but the second prank was the true masterclass in trolling.
In the lead-up to April 1, Adult Swim promoted a TV airing of Aqua Teen Hunger Force Colon Movie Film For Theaters, ten days before its theatrical release. Technically, Adult Swim made good on its promise. It did air the Aqua Teen movie... but in the corner of the screen without sound at the same time that the regular line-up was airing.
3. The Room (2009-2011)
A prank so nice they did it thrice, Adult Swim's three April Fools Day airings of The Room helped push Tommy Wiseau's "dark comedy" from relative obscurity into "so bad, it's good" movie stardom. Of course, TV standards required censoring the sex scenes, but considering what the sex scenes in The Room are like, that can be considered a godsend.
The one downside to this prank was how repetitive it became, even with Adult Swim spicing things up with new Space Ghost segments in the second and third years, though that repetition ended up being the perfect set-up to the best April Fools prank ever.
2. Double prank: Japanese Toonami and Bushworld Adventures (2018)
Either of Adult Swim's 2018 April Fools pranks would have been great enough on their own, but together they make the second-place spot on this list. Saturday at midnight, Toonami aired with a surprise Japanese-language line-up, the first time the block ever showed subtitled content. This included a stealth premiere of the first episode of FLCL: Alternative as well as Masaaki Yuasa's movie masterpiece Mind Game.
The Sunday primetime prank was a humorous response to the previous year's popular prank of stealth-premiering the Rick and Morty Season 3 premiere. Viewers got new Rick and Morty content this year, but it wasn't the show they recognized. Instead, it was a bizarre Australian short film called "Bushworld Adventures" by animator Michael Cusack. Cusack has since created YOLO: Crystal Fantasy and the pilot Smiling Friends for Adult Swim; he is also developing Koala Man alongside Rick and Morty's Justin Roiland for Hulu.
1. Toonami's Return (2012)
It started like any ordinary April Fools night from the past few years, with the opening credits of The Room playing. Suddenly, the camera zoomed out to show TOM and SARA, hosts of the then-canceled Toonami block, watching The Room themselves, and suddenly Toonami was back for the rest of the night. The block included that week's regularly scheduled new episode of Bleach, but the rest of the line-up was replaced with nostalgic anime ranging from Dragon Ball Z to Tenchi Muyo to Astro Boy.
This instantly became the most popular April Fools prank Adult Swim has ever done, inspiring a massive social media campaign to bring back Toonami for real. Adult Swim listened to the fans, and within two months, Adult Swim had rebranded its Saturday night anime block as a revival of Toonami, with all the creative packaging and loving promotion of great anime you would want from such a revival.