Any card is selected by a spectator and left protruding face down from the center of the deck. A different card – in this case, the Joker – is turned face up so it rests clearly on top of the pack.
In the blink of an eye, the top card visually changes into the original selection.
The face down card in the center is then removed to show that it has changed into what was originally the top card of the deck. Tony’s unique transposition
