This trick from David Blane is popular around the world. The magician takes 2 plastic coffee cups, cuts one in half, and fills it with coins. Then he makes a tiny hole in the bottom of the big cup, puts a sponge inside, and places the cup with the coins on it. Now all he needs to do is place his finger inside the hole. The small cup will go up, revealing the coins, and the coffee will be absorbed by the sponge. The rest is just acting!