Prank (The Batman)

"Oh, I know it! I know! X equals P.U.!"

- Donnie

History
A fellow classmate of Barbara Gordon, Donnie considered himself the class clown, even if no one else in the school did. After deciding no one in the school understood his jokes, Donnie went to an open mic stand-up, where he caught The Joker's eye. Jealous that Batman had a sidekick, Joker wanted one of his own, and chose Donnie.

After convincing Donnie (done by hoisting Donnie's teacher up on the flag pole) to join his team, Donnie and Joker hatched a scheme to hurt the GCPD. The plan failed when The Batman and Batgirl intervened; despite having gotten Batman trapped and capturing Batgirl, when it came time for Donnie (now dubbed "Prank") to pull the trigger and kill Batgirl, he couldn't. Seeing this as a flaw in his workmanship, Joker took Donnie back to his hideout. There, Joker was readying to drop Donnie into the vat of acid that transformed Joker into his current state. The Batman and Batgirl showed up just in time to stop Joker and save Donnie.

Donnie delivered the final blow to Joker and knocked him out with a quick punch from Joker's own popping fist gun.

Powers and Abilities
Donnie didn't have any super-powers or abilities. But as Prank, he did have a lot of ideas for jokes.