You will test your spectator's memory by having them try to remember various bits of information drawn on a business card.
Then, they will attempt to remember 4 different coins!
Seems easy enough until the fourth coin suddenly pops out of existence only to be found taped firmly to the business card that's been examined and in front of them on the table the whole time!
Super-easy magic with an engaging premise and a genuinely baffling finale! And, they get to keep your business card with the coin taped to it - something they are unlikely to throw away!