This trick works on the Gelato Beach level in the stage, "Wiggler Ahoy! Full Steam Ahead!". Battle Wiggler as usual, then, when you've ground pounded the worm the third time, you'll hear the boss music slow down. Before the Shine Sprite appears, press Z to view your map.

If you timed the Z press correctly, you'll hear the slower remix of the boss music! In the map mode, hit cancel, then IMMEDIATELY press the Z button again to listen to a much faster remix! This doesn't give you any extra lives or anything, BUT it is useful if you love game music!