"This World O' Mine" is a song heard in the Season Nine episode, "Die Hippie, Die".
Background
Eric Cartman attempts to appease his captive hippies, by giving them drugs and a guitar. Moments later, the room is filled with smoke and the hippies are intently listening to this song.
Lyrics
What's goin' on in this world o'mine?
There's a whole lot of killin' in this world o'mine.
Somebody's gotta help this world o'mine...