Effect: A person from the audience picks a card and sets it aside. After a little hocus-pocus, you flip over three cards of the same rank as the selected card.
Preparation:
1) Take all four cards of two suits from the deck (for this we will say Aces and Kings.)
2) Put all four Aces on top of the deck, and all the Kings on top of them. Now you are ready.
Card Trick:
1) Deal the cards into two face down rows of four: Ace, Ace, Ace, Ace; King, King, King, King.
2) Ask a spectator to point at one row of cards. Remove this row and place it on the bottom of the deck (It is no longer needed. For this, we will say that the Kings remain.)
3) Have the spectator touch, but not look at, a single card in the row.
4) Place this card aside, and put the remaining three cards on top of the deck. (That gives you one King on the table and the other three Kings on top of the deck.)
5) Deal the cards out into three piles (one King will be on the bottom of each.) Continue to deal out the cards until your spectator tells you to stop.
6) Now you can use any elimination process to bring each of the piles down to one card (which will be the King that was on the bottom.)
7) The only cards that should be left on the table are the one King that was set aside and the three Kings that were dealt into the piles. Flip the single card face up, reminding everyone that the spectator selected it. Now flip the other three cards face up, revealing that they all match.