What is the disappearing act? It is when you have a picture ,in our case a smiley face, and you have a cup full of water three fourths full.Then you put the cup on top of the picture and look at it in a lot of different angles.You will probably notice that the picture will disappear if you look at it from the side. Why is that? It is because of refraction. Here is a little video about refraction. What is Refraction