Mystery Box II

Bring out a small wooden box and place it down on the table. Have a playing card freely chosen and signed by a spectator. Shuffle it back into the deck and ask, "Do you think that I can find your card in less than ten seconds without even looking at the cards?"

Hold the deck behind your back for several seconds, then bring it out and announce, "I've found it!" Pause briefly, then continue, "And guess where it is..." Point to the wooden box that has been resting on the table all along. There's absolutely no way the card could be inside because no one has been anywhere near the box.