The Trick: You happen to be in a room with a group of friends and a pack of cards. Here's how to make some easy money out of them with a simple card trick. Start by asking someone to pick any card from the deck, show the rest of the people in the room and then slide the card back into the pack. You shuffle the deck and then start turning the cards over one by one until you see the card that your friend choose. At this point you bet everyone in the room a certain amount of money, perhaps $1 or $5, that the next card you turn over will be the one that was originally selected.
As the selected card has already been turned up, at least one of your friends will assume that they can't lose and accept the bet.
Once the bet is made, you simply turn over the card on top of the pile of cards that have already been revealed and collect your winnings.
The Explanation: Right, for all of you who can't figure out how to do this trick, here's what happens.
Take a normal pack of playing cards, shuffle them well, fan them out and ask one of your friends to pick a card. At this stage it doesn't matter what card they select. Unlike many card tricks you don't have to use sleight of hand to force them to choose the card of your choice.
Once they've taken a card, it's a good idea to ask them to show it to the rest of the people in the room. This will increase the chances of someone accepting your bet later on. After everyone except you has seen the card, shuffle the rest of the pack, cut it in the middle and let the person return their card to the pack.
This is the key to the trick. When you separate the pack to let them return the card, take a subtle look at the card that will be placed on top of their card when you put the pack together. Make sure nobody sees you doing this. This is where the ability to keep talking to distract your audience comes in useful.
Once you've placed the pack together, cut the deck a number of times, making sure that you take note of the bottom card after the last cut. If it's the card that was on top of the selected card cut the pack once more. This will make sure that your card is put back on top of the selected card.
Put the deck face down on the table and start turning the cards over one by one. Keep going until you see the card that you made a note of appear and then turn one more card (this will be the card that was originally selected by your friend). Make it look as though you're about to turn the next card, then stop and bet anyone in the room a certain amount of money that the next card you turn over will be the one that was initially chosen.
As soon as somebody accepts the bet, turn the selected card face down and collect your winnings.