Effect: Hand a spectator a deck and tell him to shuffle them a few times, then place the cards on your left hand. With your right hand, start sliding the cards back about 1 to 5 at a time until he (or she) tells you to stop, before you get to the bottom of the deck. When he says stop, tell him the card he stopped you at, and lift the cards off the deck, revealing that the bottom card is what you said.
Memorize the bottom card (say, the 8 of Spades). If y
u can't see it when the spectator is shuffling or handing you the cards, glimpse it as you square up the deck. Lay the deck face down in your left hand. Put your right thumb under the deck and your right fingers on top (lengthwise to the deck). Start sliding the cards back from the top, 1 to 5 at a time, about 1 centimeter each. As you do so, secretly slide the bottom card toward you with your right thumb. Say, "Tell me when to stop before I reach the bottom of the deck." When the spectator says stop, slide off all of the cards you have already pulled back into your right hand. As you do so, slide the bottom card with your thumb under the cards you are removing. Before you reveal the bottom card of the cards in your right hand, say, "The card you told me to stop at is the 8 of Spades." Then reveal the bottom card of the pile in your right hand.