Birds of a Feather Fool Around Together The New Adventures of Batman : Season 1 Episode 13

Penguin creates the Crime-Slime, which has the capacity to turn anyone evil. He uses it on Bat-Mite, turning him from a harmless imp into a villainous little monster. Whilst trying to return him back to normal, Batman and Robin must also deal with the Penguin and his new creation before any more damage is caused.