They call this "ruining your childhood," although I can't understand why adding an erotic component to a cartoon character ruins anything.
(All pictures courtesy of the original artists.)
1. A grown-up Bam Bam from The Flintstones
2. Child genius Dexter from Dexter's Lab grow into an adult science nerd, being whipped by his nemesis Mandark.
3. Bender prepping Fry from Futurama.
4. Max Goof aroused at the beach. He never said "Hyuck." That was his father Goofy.
5. Mordecai and Rigby from Regular Show
