Les:  I’m goin’ down to South Park. Gonna have myself a time.

Kyle & Stan:  Friendly faces everywhere. Humble folks without temptation.

Les:  Goin’ down to South Park. Gonna leave my woes behind.

Cartman:  Ample parking day or night. People spouting Howdy Neighbor!

Stan:  Heading on up to South Park. Gonna see if I can’t unwind

Kenny (muffled):  I like girls with big fat t*tties, I like girls with big vaginas  (trust me, these are the actual lyrics)

Les:  Come on down to South Park and meet some friends of mine.

Third season change:

Kenny (muffled):  I've got a 10 inch penis. Use your mouth to help me clean it.

Seventh Season change: 
Sometime I'll be old enough to stick my d*ck in Britney's butt

Thanks goes to Chris W. & Nice G. F. for some help.