Bob Geldof formed the punk group Boomtown Rats in 1975. During the band's existence, it moved from the pure energy and aggression of hits like "Looking After No. 1" to the more sophisticated but still provocative "I Don't Like Mondays" (its title derived from the answer given by a San Diego schoolgirl when asked why she'd killed her classmates). The band became a moderate success in the U.K., though it never really broke through in the U.S.