I agree 100% with Jim Caple’s thoughts today on the music for closers coming into the bullpen. I would also suggest “Ride of the Valkyries” by Wagner, for a nice classical touch.
But if you really want to throw them off, why not come in with something like “Baby Elephant Walk” or the Looney tunes theme? You just need to distract a batter a little bit to make a home run a long fly ball, right? And what could be more confusing to a batter than that?