Bring out a pack of Bicycle poker-size cards. The card box is red. Explain that this is a very odd deck because inside the red card box is a blue-backed deck of cards. Strange that the card company would make this mistake. Remove the cards and place them on the table. Offer to fix the card company's mistake. Hold the card box in your hand. In the blink of an eye, the card box changes from red to blue. It happens so fast they won't believe their eyes. But, there it is. Red to blue in a wink.