The "Bad Girls" are prostitutes. Summer got the idea when she was working for Casablanca Records in Los Angeles, and she sent her secretary on an errand, which took her down Sunset Boulevard, which known for illicit activity. The secretary, who was black, told summer that the police harassed her, assuming she was a working girl. This raised the ire of Summer, but also provided inspiration for the song, which came together when she started ad-libbing lyrics in the studio.