Heh, my husband and I have a "psychic" bar trick based on the same principle, but using pennies instead of Zener cards (used to be matchsticks until everything went non-smoking), and a cocktail napkin and a drink for the cues. It worked every time, and we would get free drinks for being psychic!
And yes, we would do a reveal at the end. After the free drink.
There is a similar one my friend and I would do at parties. Using a deck of cards. I would shuffle the cards a few times until I got something on the bottom of the deck I wanted. A card that had a large number, say 7-9, as there would be 7-9 "diamonds" (or whatever suit) laid out on the card itself in a certain layout. This was the key.
Then I would lay out the cards, on the table, in the same pattern as the bottom card of the deck. My friend is out of the room during all this. I then would ask the person to pick a card, and I would telepathically "send" this card to my friend. He would enter the room, and I would be holding the deck of cards in a manner so that he could see the bottom card, and my thumb would be placed over the specific position / card that was chosen.
Fooled people many times.