STARTLING! Ask your spectator to name any card, and you agree to make the selected card vanish. The deck of cards is placed in the box, you give the box a tap, and declare that the card is gone. To prove it, the box is turned over- the entire deck is gone, and the whole front of the box is missing, revealing an empty box!
Seems totally impossible, but it is SO EASY! If you can slide a deck of cards into a card box, you can do the trick! WOW!