Quicksand by Jay Grill

Ver 1 :: Have a coin audibly vanish from the card box that the spectator is holding onto and have the coin appear on top of there chosen signed card. The cards are know where near the box when it vanishes!

Ver 2 :: Visually have a signed borrowed coin, melt through the top of deck right before there eyes, to have it sink half way through the other cards and land on there chosen signed card... that the spectator cut to!