Milk Glass Illusion
The magician starts out displaying four differently sized glasses, which are lined up from smallest to largest and are all shown to be empty. The smallest glass is picked up and filled with milk from a pint size milk carton. The small glass is displayed, and the magician looks at the glass and shakes his head, because he wants a bigger glass of milk. Unfortunately, there is no more milk in the milk carton. So instead, the magician pours the milk from the smallest glass into the next bigger glass in the line up. The milk fills the glass to the top!
The magician takes this glass and fills up the next biggest glass in the line up, and it also fills the glass to the top! The milk is seemingly multiplying from glass to glass. This is repeated all the way up to the largest glass. The magician has filled up the largest glass from a tiny glass of milk!
Now with the largest glass filled, he gives a big smile and then starts to fill the three empty glasses up from the largest down to the smallest. The largest glass fills up the other three glasses!