Can anyone give me the name of the epsiodes (and seasons they're in) where Cartman says this catchphrase. It's one of the funniest things I've ever heard in my life.

i can't really recall it but he does say it a lot in one of the seasons

it's a standard Cartman catchphrase, especially in the earlier seasons before they really began fleshing him out

I think my favorite "Screw you guys, I'm going home" moment wasn't from Cartman, but from an adult dressed up like him, in "Spontaneous Combustion". Randy's got 4 adults dressed up like Stan, Kyle, Cartman and Kenny to try and re-enact why Kenny spontaneously combusted, and the fat guy dressed up like Cartman said "Screw you guys, I'm going home" and left :)