1. Roll up your sleeves, take out the coin (the larger the better) and cover it with a handkerchief.
2. To prove to your audience that the coin is still in your hand, even though it's covered by a handkerchief, invite various audience members to reach under the handkerchief to verify that the coin is still there.
3. Save your friend for last. When your friend reaches under the handkerchief, he or she simply takes the coin.
4. Utter some magical words and whisk away the handkerchief to show that the coin is gone.
5. Reach into your pocket and display the coin that you placed there earlier.
