I had this conversation with some co-workers yesterday...do you have a particular song that you think of when you're trying to get a different song out of your head?
For instance, if I get "This Is The Song That Never Ends" stuck in my head, I simply turn to "Yellow Submarine" to relieve my suffering.
My co-workers listed: Brandy, Hang On Sloopie, or "anything on my iPod".
Everyone's choice of rescue song was subject to much ridicule. But I figure, if it works, it works.