La pièce à l'eau (Vanishing coin in water)
Borrow a quarter (or any small coin) from a spectator. Placing the coin under a handkerchief, you ask the spectator to drop the coin into a small glass full of water. When they remove the handkerchief from above the glass, the coin is nowhere in sight ! Alternatively, you can toss the coin into a glass of water. It appears to pass through the glass and table and is caught by the magician below the table. Requires no sleight of hand. Easy to do !