THE EFFECT: While sitting at a table you show your audience an ordinary sugar packet. You immediately throw the sugar packet into the air and stab your index finger right in it. Your audience is dumbfounded how fast you are.
THE SECRET: You actually have two sugar packets in your hand. One is already stabbed into your index finger of any hand (but you must hide that hand). As you throw the sugar packet into the air you actually catch it with your hidden hand and show the one that was already on your finger. It will look like you have just stabbed the sugar packet very fast!