You offer to take the spectator on an imaginary walk through a casino. You instruct him to imagine going through the door of the casino and visualizing people playing a game of Craps. Ask him to imagine someone throwing a set of dice and the dice landing on the table. Tell him not to announce the total.
You show some napkins or Post-It notes and point out that they are numbered 1, 2 and 3. Take a napkin or Post-It note #1, pretend to read their mind, and then write down the total of the dice as you visualize it in your mind. Then ball up the napkin or paper and drop it into an empty cup. Now that your prediction is captured, ask them to announce the total of the dice, so they cannot later change things. Then ask them to imagine going further into the casino and visualize a spinning roulette wheel with the ball starting to slow down. Have them visualize where it lands from 1 to 36, but do not say anything. You write down a prediction on #2, ball it up, and toss it into the cup. You ask him to announce the spot on the roulette wheel where the ball ended so that they cannot change their choice later.
Finally, you ask him to imagine moving on to a Black Jack table and to visualize the dealer's cards with one card face up and one face down. You now ask him to imagine walking behind the table and behind the dealer to peek at the face-down card. You write down a prediction on #3, ball it up, and toss it in the cup. Now ask them to announce the face-down card that he peeked at. Lastly, reveal all three predictions and show that all three are correct.
Supplied with instructions and special gimmick for the fantastic mental routine, and many other possible uses that you can carry with you in your pocket.