Ben:How would you like to learn how to win a free drink with a pack of cards?
Female:I would definitely like to learn how to do that.
Ben:I'll show you. It's a little game. Would you like to mix these up for me?
Female:Okay. Any particular way?
Ben:Doesn't matter, as long as they're mixed.
Female:Okay. Is that good enough?
Ben:Perfect. Go ahead, take any card that you like. Memorize it, show it to the camera. Make sure I don't get to see it. Good?
Ben:Okay. Place it right on top, there. I'll put these here. Would you give them a cut for me? Perfect. Would you like to give another cut?
Ben:The last cut's optional; it's up to you.
Ben:Why not? All right. Look at the cards, but don't tell me if you see your card, all right? Would you buy me a drink if the next card I turn over is your card?
Ben:I think you owe me a drink.
Female:How'd you know?
Ben:You want to know?
Ben:All right. This is a great way to win a drink in a bar because everyone thinks, "Aha. The magician messed up. He's never going to get it." Here's how it works: It uses an old principle called the Keycard Principle, and I'll walk you through how that works.
The first step is I have you shuffle the cards. They can be mixed any way, it doesn't matter. Perfect. Then I take the cards back and I have you select a card. While you're looking at the card or showing it to your friends, I do something. I very subtly glance at the bottom card of the deck. Right now, I'm going to have a look and I see that it's the 9 of Diamonds. I know in my head the bottom card is the 9 of Diamonds, and I'll show you how that comes into play.
I take about half the deck and I place it on the table. Then you place your card there. When I put the rest of the packet on top, I now know the 9 of Diamonds is directly on top of your card.
Female:Then I'm cutting that.
Ben:Exactly. That's why it fools people, because you can't shuffle the cards. You can cut the cards, because if you're cutting the cards, the 9 of Diamonds will always stay directly next to your card, which I now know, is the 9 of Spades. However, if you cut right at the 9 of Spades, it's still next to it. If you cut between the 9 of Diamonds and the 9 of Spades, the 9 of Diamonds is on the bottom and their card is on top. If you cut directly above, the 9 of Diamonds will be the first card; their card will be the second card.
It can never actually get separated unless one's on top and one's on the bottom. The way you check for that is you just make sure that the bottom card, when you're done cutting the cards, isn't still the 9 of Diamonds. You can cut it and complete the cut as many times as you like.
Now, I have no idea that your card is the 9 of Spades this time. As I turn the cards over, and it's very important that you say, "Look at the cards, but don't tell me if you see your card." This way, the person won't miss the card as they're looking. You slowly turn them over, and I do this until I see that 9 of Diamonds.
Ben:You'll notice that I'm only using about half the deck, because sometimes, it can take a very long time. Now I see the 9 of Diamonds here, which means I deal another card, which is your card, and then I say "Aha," and I point to the card that isn't their card.
Female:[inaudible : 04:08]
Ben:Exactly. I say "Would you buy me drink if the next card that I turn over is your card?" At this point, they almost always say, "Yes." Then you turn their card over.
Female:Great. So clever.
Ben:There you do it. That's how you win a drink with a pack of cards.