Factory Blanks by Tom Stone
A blank deck that isn't one!
Imagine this: you take a spectator in front of you (stand-up demonstration) and show him a deck of cards that you explain have not yet been printed.
The whole audience sees an empty game. The spectator brought to the front is now free to choose a card and remember it (best comedy).
But you can guess which card the spectator seems to have just imagined! Better said, you record the card for all spectators to see and then let him name the card!
A miraculous match that can be repeated immediately.
With German PDF instructions!