Get a nut and balloon. And you can make some crazy sounds.
You want a nut from a hardware store not one that you eat.
Also this is great for class parties. I've seen people doing for them before and kids won't stop with them. I made this instructables to get more people to know about it and get a instructable on by page.
Step 1: Blowing Up the Balloon
Blow the balloon up to a good size, then place the nut inside. Tie the balloon up as you usually do.
Oh yeah the cartoon there is just a joke. :)
Step 2: Make the Music
After you tied your balloon. Your ready to go. Place the balloon side ways and move your wrist in a circular motion so the nut is moving in a straight circular path on the inside edge of the balloon. If you hear a whizzing sound your probably doing it right. You can make a lot more noises to just be creative.