Kyle: Stop calling my mom a bitch, Cartman! Cartman: ooOOOOOOoooooooohhh! (starts singing "Kyle's Mom is a Stupid Bitch (in D-Minor)".) (Everyone in the room eventually starts having fun and claps to the beat of the music, except poor ol' Kyle, of course.)
That was a classic, Cartman finding a way to really piss off Kyle and going for it! Let's see, how many other times has Cartman gone overboard? Anybody?