What you need: Two similar card decks and one card with the same pattern but in another color. Let's say, you have two red decks of cards and one card with the same pattern on the back, but in blue. I will call this card the blue card.
Preparation: Take out of the two card decks two similar cards (let's say the eight of spades). You put both decks on the table, face down. Now you take the first deck, put one eight of spades on top. On top of the other deck you put the blue card. I
looks like you have two different decks: a blue one and a red one! You take the other eight of spades and hide it somewhere. It's a lot of fun, when you can hide it in your friends pocket or anywhere like this. Another thing you need to have is a towel. When you have done the preparation you are ready to perform:
Performing: You ask for a volunteer. When he steps forward, you take the red deck with the eight on top and move it under the towel. As soon as your hand is covered by the towel, you turn the deck face up (the audience shouldn't notice that). Now you ask the spectator to cut the deck which is laying on your hand. He will lift the towel and a part of the deck. You move your hand down and turn the deck again, while it's still under the towel (it takes a little bit of practice to do this fast and without the audience noticing anything). Now you show the part of your deck and ask the volunteer to take the card which is laying on top. Then you put the rest of the deck under the towel, turn them face up again, ask the spectator to put his cards back on top of yours. Before you remove the towel, you turn the deck again (it's facing down again). Now you ask your volunteer to show the card which he has chosen to the audience. As soon as he has done this, you tell him/her to put it back somewhere in the deck. You can even offer him to shuffle the deck. When he is ready you say a couple of magic words and tell the audience that you have transmitted the card to another place and where they will find the card. When the audience is looking at the place (let's say in your friends pocket) you have to take advantage of the moment and switch the blue card from the top of the second deck on the top of the deck which you just have used. The audience will be quite surprised, when they find the right card at a total different place. To prove your magic knowledge you can show the second deck of cards and let the audience look for the eight of spades. They will not find anything!
Watch out: this is not an easy trick and it needs to be performed really well. There are a couple of spots where the audience could catch up, when the trick is not prepared or practiced enough. Please feel free to change the trick. You can also just perform the part with the towel. It's a really nice trick to force a volunteer to choose a certain card, which you know in advance!