The Changing Ball Trick
Take a ball in each hand, and stretch your hands as far as you can, one from the other; then state that you will contrive to make both the balls come into either hand, without bringing the hands near each other. If any one dispute your power of doing this, you have no more to do than to lay one ball down upon the table, turn yourself, and take it up with your other hand. Thus both the balls will be in one of your hands, without their approaching each other.