Magician borrows or produces a deck of cards.
The spectator freely selects a card, signs it and draws a little mouse on the card face.
Magician takes the card places it in the deck and allows a the spectator to shuffle the cards.
The magician takes a mousetrap, sets the trap and places it on the spectator's outstretched hand.
One at a time cards are taken from the top of the deck and placed on the mousetrap.
Nothing happens until the card with the mouse drawn on it touches and springs the trap, causing it to close on the selected card.

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