At the 224th annual Grampies Award Ceremony, all Cartoon Network characters participate for their chance to win a Grampie only to find out it was rigged for Uncle Grandpa to win everytime.
In the epilogue "The Grampies", Uncle Grandpa hosts an award show, featuring cameos from other Cartoon Network shows, such as "Dexter's Laboratory, Johnny Bravo, The Powerpuff Girls, Samurai Jack, The Grim Adventures of Billy and Mandy, Foster's Home for Imaginary Friends, Adventure Time, Regular Show, Ben 10: Omniverse, The Amazing World of Gumball, Steven Universe and Clarence". Including speaking parts from Natalie Palamides, John DiMaggio, Zach Callison, and Roger Craig Smith, reprising their roles as Buttercup, Jake, Steven Universe and Belson, respectively.
Sumo from Clarence is shown with eyelashes, although he doesn't have visible eyelashes in his home series.
Although there was a vast of Cartoon Network Characters that participated, not all of the major characters from all the shows on Cartoon Network were featured.