Try to remember the previous song that you actually liked which played endlessly in your head (not something that was annoying). Your mind has probably come up with a way of blocking out that old tune. Deliberately play that old tune in your mind and try to use it to drive out the current endless song. The old tune should quckly stop playing after establishing itself over the current song.

Gary

p.s. My family and I were stuck in the "Pirates of the Caribbean" in Disneyland for almost an hour after it broke down. I had "Yo ho, yo ho, it's a pirate's life for me...." semi-permanently etched into my brain. Hog tying an al Qaeda terrorist and putting him next to one of those singing pirate dummies would be an effective way of extracting information. Of course, the ACLU would probably sue to prevent such heinous torture.