Apply high school physics to amaze your friends and win free drinks.
Effect: Pour a shot of whiskey, and set it next to a shot of water. Challenge your friend to figure out a way to get all the whiskey into the water glass, and vice versa, WITHOUT using a third vessel of any kind (including your mouth!).
Secret: Whiskey is lighter than water (the better the whiskey, the better this works). Place a business card over the glass, turn it upside down and place it on top of the whisky glass. Then, pull the business card out just the tiniest amount, so a small crack opens between the two glasses...and wait. The lighter whiskey will slowly trickle upwards to the top of the water's shot glass, while the water trickles down. It's a really neat looking effect! After 10 minutes, the two drinks will have completely swapped places.