Blank and Blue Deck
Effect: A card selected from a blue deck is placed into a red deck. A second spectator is shown the deck face up and is asked to say stop on any card. That card, when turned over is seen to be the blue-back card selected by first spectator. The magician places the blue card back on top of red deck, snaps his fingers, and when the deck is spread it has turned all blue. Another magical pass and when the cards are flipped over they are seen to be all blanks.