Playlist Central

Britney Spears' latest contribution to pop music's math textbook, "3," is a celebration of bedroom-floor activities involving more than two people, and we don't mean vacuuming. She coos naughty stuff about "Peter, Paul and Mary gettin' down." But Ms. Spears is not the first pop star to deal with said multi-partner practice; others have documented different lovemaking activities as nontraditional. Herewith, an inventory of sex-obsessed songs that opt for flavors other than vanilla.