This is a diabolically simple method for a card trick that will fool even seasoned magicians:
How it looks: You begin by running through the deck, pulling out random cards that you feel a “psychic connection” with. After pulling out 15 to 20 of these cards, they are shuffled, and your subject chooses one and replaces it in the pack. All the psychic cards are then thoroughly shuffled both by you and your target (hell, you can even shuffle all the psychic cards into the plain-jane ones, as well). No matter how well they’re shuffled, after you run through the entire deck of cards, you’ll know which one belongs to your subject.
How it’s not done: There’s no sleight-of-hand here. There’s nothing to practice. No tricky deck of cards, no secret markings, no hidden accomplices. Everything is done simply and in the open. You can present it as an ESP feat, or (more impressively, I think) a demonstration of your ability to read the facial expressions of your friends.
I originally learned this trick from my uncle when I was in second grade, yet I’ve seen it fool professional magicians. The method’s just too dead-simple, so it flies right under their radar and utterly slays them.
The Secret: It all begins when you pick your “psychic cards.” As you look through the deck, you’ll notice most of the cards are perfectly symmetrical: they look exactly the same no matter which direction you turn them. There’s no “right side up.”
However, depending on the design, age, and condition of the deck, you’ll be able to find 15-20 cards with a “one way” orientation: cards that can be arranged to have a “right-side-up” and an “upside-down”. These will usually be numbered cards in hearts, clubs, and spades (though you can also use the seven of diamonds). Keep an eye out for “natural marks” as well: stuff like a creased corner, a misprinted card, random stains or splotches, even warps in the cards can all be used to give cards an orientation.
As you pull out your psychic cards and place them into a pile, discreetly make sure to orient them all right-side-up (and from now on, make sure not to disturb the orientation when shuffling). Have a card selected from the pack, and when it’s returned, make sure it’s in the reverse orientation to the rest of the pack. Take a look at this picture, and see if you can spot the one card reversed from the others:
All of the cards shown have the majority of their pips pointing upwards. The six of clubs has four pips pointing up, and two pointing down. The nine of clubs has five pips pointing up, and four pointing down. Diamonds don’t really have a direction to point, but the extra pip on the seven of diamonds is oriented to be on top. Only the three of spades is upside-down, with 2 pips pointing down and only 1 pointed up.
With some decks, you can pull the same trick using the designs on the back of the cards, but I don’t recommend it. For starters, using decks with a “one-way back” is a technique very well known to even amateur magicians, and worse yet: even if they don’t know a thing about magic, it’s usually pretty obvious to most people when all the backs of the cards are arranged the same way except for one.
That’s the beauty of this trick: using the orientation of the pips is so subtle that nobody, not even magicians, will notice the difference.