Without you even touching the deck a spectator thinks of any card and removes it from the deck and hides it in their pocket. You then take another deck and claim that you are going to try and choose the same card that the spectator has hidden in their pocket. You remove one card and the spectator removes the card from their pocket, however it is NOT the same card. You ask for a Second Chance to prove that you have chosen the same card.
Turning over your card it is seen that the spectators 'Thought of Card' is written on the back, proving that it is the Same Card!
Sounds impossible? It's that good!