The Setup:

Present a shot-glass full of whiskey and another filled with water. Challenge someone to make the two liquids switch places using only their driver’s license.

The Secret:

Each shot glass should be filled to the brim; one with water and the other with whiskey. Place a laminated driver’s license on top of the shot-glass of water. Press the license on top of the glass as you invert it and center the glass of water over the glass of whiskey (Fig. 1). Hold the uppermost shot-glass full of water in place as you lightly tap the driver’s license toward the mouths of glasses until you create a small gap or opening.

With a small gap between the two glasses the magical transformation will take place as the two liquids pass through one another. For this reason it is best to use a dark colored whiskey like Jack Daniels®. In about ten minutes the whiskey will fill the top glass and the water will fill the bottom glass. This works because the water is a more dense liquid so it falls into the bottom glass forcing the whiskey into the uppermost glass. Even knowing how this works it is still amazing to watch. If you don’t have any whiskey handy, then you can also perform this stunt with red wine.

Right now I’m on a whiskey diet. Last week I lost three days.