A bill or a currency note is borrowed from a spectator, folded, and dropped into a sealed clear crystal box through a slot on the top. Hand the box out to the spectator, and he will not be able to open the box unless he learns the clever secret. But you

The performer displays two transparent empty glasses and his hands completely empty. Both glasses are placed on each other mouth to mouth. He holds the glasses like a cocktail shaker and moves it as if making a mixed drink.