Instructions
Shake your hand gently to relax it. If your hand is stiff, it will be more difficult to achieve a loud snap.
Push your thumb against your index finger as hard as you can. You must exert a lot of force with your index finger. Hold your three remaining fingers slightly up to keep them out of the way while you snap.
Slide your index finger toward your palm while you push your thumb in the opposite direction. Concentrate on slapping your palm with your index finger as hard as you can.