You fan the cards and the spectator takes the one card that you already know the identity of. The possibilities are endless for what you can do with this. It feels like a completely free choice to the spectators, but you will start to hit the exact card about 95% of the time if you use these simple techniques about the classic force below:
First, a little history on this trick...
The classic force.
Many beginner magicians do not try this because they think it takes too much practice. That is the secret to this trick. Every time you are having someone pick a card, you should try to force a card to them.
If you miss and they pick another card, have a different trick ready so that it doesn't look like you messed up. If they take the card, great! You are ready to perform a miracle.
Read their mind, locate the card, pull a prediction out of your shoe with that card on it, etc...
Here's how to do the classic card force...
Start with the card you want to force on top of the deck. Cut the deck in your hands so that the top card(force card) is now near the middle of the deck and fan the cards. As you do this, keep an eye on where this top card is. Naturally it is spaced out a little more than the rest of the cards. Fan the cards with two hands. It's okay if there is a natural gap, that will help you keep your eye on the force card. If you want, you can even put a light pencil mark on the card as you are starting to learn this trick.
Start to move the cards from the left into your right hand by pulling them over with your right thumb.
Timing is the key to this, but so is a little "honest" psychologicial manipulation. Ask the person to pick a card. (Specificially, I'll say "Pick any card you like, and then mutter "It doesn't matter") That usually gets them to relax a little and makes it work even better! Now, as they reach up to pick a card, time it so that at about this time you get to the card you want them to take and make it easy for them to take this card. Nonchalantly spread the cards a little more and guide this card right into their outstretched finger tips.
As you try this, you're going to be really surprised about how easy it is to force feed a card right into their fingers just about every time. You can even enhance the effect if at the end of your trick you reiterate that they could have taken ANY card and it would have worked the exact same way. Of course, your secret is safe with me that if they had picked any other card, you would have had to do an entirely different magic trick!
Practice this and you can do it anwhere, with any deck of cards, under all kinds of conditions. I love it! You will too.
There are a couple of other good ways to force a card, and they are explained at MagicTrickVideos.com for just a few dollars. Pay for the trick, and you have instant access to a video explanation. Since you now have just learned how to do the classic force, there are several tricks on that site that will allow you to enhance it even more!