Take two pieces of paper that are exactly the same, and crumple one into a ball. Make the ball as flat as possible. Hold the second piece of paper while placing the crumpled paper behind it in the top corner with your left thumb. Tear the second sheet into multiple pieces and stack the pieces together in your hand, but keep the strip with the crumpled paper against it closest to you at all times. Crumple up the pieces to make it look like you're making another ball. Place all of the paper in the palm of your hand, making sure the original crumpled ball stays out of sight. Reach into your hand and gradually uncrumple the original paper. Show the original piece of paper, and hide the torn pieces behind it, pressed against your thumb.
Attach a loop of clear double-sided tape to the side of an empty foam or paper cup. Hold the cup in both hands while facing the spectators and declare that you will try to make it float. Keep one thumb pressed against the tape on the cup as you appear to focus all your attention. Gradually open up both of your hands together while your thumb is still stuck to the tape, keeping that thumb away from the audience's point of view. Push your thumb and the rest of your hand slightly toward the audience to make it look like the cup is floating away from you. Follow it, then grab the cup with both hands as though keeping it from getting away.
Place the cup on the table along with a sheet of paper or a paper napkin (the sheet works best) and a coin. Place the mouth of the cup over the coin, then drape the paper over the cup, making sure the paper folds over and conforms to it. Move the cup and paper aside, so the coin is uncovered, and start talking about the coin; this causes the audience to focus on the coin, rather than the cup. Meanwhile, move the cup toward you and off the table, letting it drop into your lap. Keep the sheet of paper on the table, so it looks like the cup is still under it. Move the paper back toward the center and lift it up, showing that the cup has disappeared.