I swear this is true. My friend Cindy (she was in her twenties at the time)thought the guy was singing don't masturbate with a diet shake. Don't ask me how she thought these lyrics could possibly have made sense in any context. There was another song out at the same time - don't know the name or artist, but the line was: "Nobody's gonna break my stride..." Cindy thought that was: "nobody's gonna break my spine" (let's hope not!)
