Pitchfork

Standing blindfolded inside bullpens, back-flipping into lakes, and stapling your butt cheeks together just isn't the same without an original soundtrack. Enter Karen O and Peaches. For the upcoming movie Jackass 2, the Yeah Yeah Yeahs frontwoman and the queen of electro-sleaze teamed up with Johnny Knoxville to record a song entitled "Backass".

Karen O told Billboard.com last week that the collaboration transpired "because [Peaches] was in L.A. at the time, and we just whipped out a little tune that makes you want to smash heads." Although Johnny's vocals might not be heard in the movie, Karen O assures that "he's quite a crooner."

Jackass 2 hits U.S. theaters Sept. 22. Wolfmother also contribute a song to the soundtrack ("The Joker and the Thief") and are currently shooting a video with Knoxville and other cast members in Australia.