This is very crazy - and it's easy to do!
You take a deck of playing cards out of a black holster. Tells the audience that this is your memory holster. You're terribly forgetful and can never remember where you put your stuff. You put the deck back in the holster while explaining that once it's located there, you always know where it is (...) Smart - right?
But still, it goes wrong. When you just a moment after turn the holster on its head the card game is gone! Completely gone! The crowd does not believe their own eyes, but the deck is completely gone.
Genius principle that almost cheats yourself!