Ask a volunteer to pick a card from the deck, then return it and shuffle the deck. Standard procedure....so far!
Now this is where things get interesting! Pull your Credit Card out of the wallet, present its front and back to the crowd and lay it facedown on the table. Whilst doing this, present the volunteer with the following dare; "I'll make you an offer you can't refuse. I'll try to read your mind and find our which card you picked. If I get it right, you owe me a dollar, but if I miss, you get to go shopping with my credit card!"
While in deep concentration, you go through the deck, extract the card you settled on, and place it on the table. "Wrong Card!" he'll declare victoriously. Once he does, ask him to announce the correct card. "The eight of diamonds," he'll say. You ask him to turn the credit card over. Just imagine his face, when he'll realize that the figure in the credit card is actually holding the eight of diamonds.