To set the trick up, place the double-backed card ninth from the top, in a face down deck. Hand the first five cards to the spectator while you take the next five, one of which is the double-backed card.
Fan your cards to show them all face down and instruct the spectator to do the same. Explain that he must do exactly as you do for this trick to work. The first move is to turn your top card face up and place it on the bottom of the deck.
Take the new top card and place it at the bottom of the deck WITHOUT turning it over. This is actually your double-backed card.
Repeat Step 1 in which you take the new top card, turn it face up and place it at the bottom of the deck. Then turn the next top card underneath the deck without turning it over.
Fan your cards open and have the spectator do the same. You should have two face-up cards alternating with three face-down cards. The spectator's packet will appear the same as yours.
Close your packet and have the spectator do the same. Next, turn the top card face up, but leave it atop the deck. Now, turn the entire deck over in your hand.
Turn the top face-up card, face down on the stack. Fan your cards to show all five as face down. When the spectator does the same, he will have one card face up. This will boggle his mind as you both literally executed the SAME actions.