Effect: You tell your volunteer that you're psychic and that you can pick out whatever card he (or she) is thinking of. Explain that this trick depends on him, so if he doesn't concentrate hard enough, it won't work. After he has the card in mind, you pick up the deck and look through the cards. After a moment, you set the deck face down in front of the spectator and announce a card. If this is the correct one, then he is amazed (and you can start your own 900 number). Since this seldom happens,
When he says it's not his card, tell him that he didn't concentrate hard enough. Tell him to take the top third of the deck and shuffle it. Then he is to take the whole deck and find his card. When he does, he is to put it on top of the deck. Then tell him to take the bottom third of the deck and shuffle it and put it on top of the deck. Then tell him to cut the deck.
You pick up the deck and look through the cards. After a second, you put the deck face down in front of him again and ask him what his card was. When he announces his card, you flip over the top card on the deck and it's the same one.
Card Trick: When you fan through the cards the first time, count to the 26th card from the bottom (i.e., from the right end). This will be your "key card." Announce it as the spectator's card. Usually you'll be wrong, but that's OK, it's part of the trick. Follow the patter above completely. When you look through the deck the last time, find your key card and count to the 26th and 27th cards above it. Put one on top of the deck and one on the bottom. Memorize their values or suits. Lay the deck face down and ask his card. When he tells you, either flip over the top card if that's the one, or flip over the deck and show the bottom card.
The reason that it's one of two is that it all depends on where he finds his card after you've found the 26th one. If his card is below the key card, then when he brings it to the top of the deck, it will be 27 cards beyond the key card.