Listen to Hidden Tune
When you're at an area with no enemies around, you can try out this neat (but useless) trick. Take out a bomb and hold the kick button (the same button used to take the bomb out). Joe will then juggle the bomb and whistle a part of the Mario theme tune. If you jump up in the air and do the same thing, and Joe will whistle a different part of the Mario tune. You have to listen closely to hear it.