An endless list of possibilities for this trick, the double folding quarter. 

One of the most talked about effects in magic has always been the coin in the bottle. Many magicians have built their reputations on this trick alone. The effect has a tremendous impact on laymen. You borrow a coin and an empty bottle. With the spectatior holding onto the bottle you apparently knock the borrowed coin through the bottom of the bottle. After all has been examined, you proceed to shake it out through the neck of the bottle.

Make the quarter appear or fit into places it has no business being and pull it back out to truly mesmerize the audience.

Please supply your own real quarter for a switch - or borrow one from your spectator.