You have a deck of cards, and you show your spectator the Jack of Spades. You put it back onto the deck and hand it to them. Then you show that you have a Two of Clubs. You wave the two above the jack, and the to cards "switch places".
Step 1: The Set-up
This trick does require some setup of the deck.
You will need:
A deck of cards.
Two of the same cards. They must look exactly alike.
(in this case, I used the two of clubs).
Get your two cards (I'll just say twins). Put an indifferent card between the twins. I used the jack of spades.
Step 2: The Double-lift
A doulbe lift is what it sounds like. You pick up two cards, but one card it hidden beneath the other. To preform this, the easy way is to just pick up two cards, and put them back. To do this, hold the cards face down in your left hand. (Lefty's, just vice-versa). Put your right hand ontop of it and use your thumb (should be behind the deck) and pick up two cards.
Oce you have done this, release the top card, and it should come down onto the bottom card.
Then, with your middle and ring finger at the top, and thumb at the bottom, pick up the cards.(in the picture, I'm only holding the cards from the bottom.)
Step 3: Fooling the Spectator
Show the spectator the deck face down.(don't give it to them. Your twins with the indifferent card should be on the top).
Now, with COMPLETE controll, preform a double lift, and show them the indifferent card. Put it back on the deck, and pick up the top card. Tell your spectator to hold out his hand, then put the card onto the hand facedown. Now, tell him to put his other hand ontop of the card. I like to say "keep it from escaping". It misleads them to not look at the card.
What they don't know is that instead of the indifferent card, you put one of the twins in their hand.
Step 4: Fooling the Second Time, and the End
Now, preform another double lift. If everthing is done correctly, the card that you'll see is the other twin. Tell them:
"Ok, now that I've given you the jack of spades, I'm going to take the two of clubs."
Show the two to them. Make sure not to revealed the hidden card.
Put the two cards back onto the deck, and takeoff the top card, which is the jack of spades. Now, it's all acting. You can wave the card over their hands, flip yours over, then theirs, then they'll freak out! (I promise! But it only works if it's convincing enough.)