Cartman has so many great ones, but these are a few of my favorites.
You must repect my authoritah!
Hippies. They say they want to change the world, but all they do is smoke pot and smell bad.
(To fat camp leader) Well, I'm pretty pissed off right now, how are you?
(While playing goalie) I'm not fat! I've got a sweet hockey body!
and when Cartman gets the glasses and the boys ask him why they're stapled to his face.....
"I'll tell you why! One...my doctor's a goddamned asshole...and that's about it!"