You show a glass with a piece of rubber sealing the mouth. The rubber is fastened with a rubberband so nothing can get in or out. On top of the piece of rubber are two coins. A spectator chooses one of the coins. The other coin is removed and the spectator is instructed to push down on the remaining coin with their finger. Amazingly the coin penetrates the rubber and is now sealed inside the glass. They actually feel the coin penetrating as they push down. Great magic!