[TB Tabby]

I remember the ending to an episode of Tiny Toon Adventures: Plucky rigged a viewer request system so they'd request a cartoon starring him, and said cartoon was a nonstop stream of violent sight gags at his expense. At the end, he'd had enough and said the viewers could see whatever they wanted, and he turned into Buster and Babs.

Oh yeah, I just remembered another one from the comic strip Safe Havens. Samantha Argus, biology grad-student, gets unstable DNA as a result of her numerous Process-y experiments. She has a sneezing fit that turns her into different cast members with every sneeze. When it finally ends, she's stuck looking like her own mother.