A great kids trick!

Effect: Have a child come up to help you with a trick, but before you have them touch the props, have the child wipe off their hands on the towel. When you take the towel back there are black hand prints all over the towel!

A great routine is to tell the child to give you a hand, grab their hand and say "Oh, I ment the clean one." Let go of his/her hand and grab the other hand and say "Oh, that was the clean one!" Then you can go into your case and get a fake hand and say "don't worry I've got my own... This one was from a child that was talking to much." Then go to the towel.