Place a red ball in your hand and ask the spectator to keep up with it as best they can. Hold up both hands and ask the spectator where the ball is now. The spectator can see a little red sticking out of your hand and calls to it. To their suprise as you open your hand that the ball has now become a square cub and the ball is now in your pocket.
Ball to Square
This trick takes no sleight of hand at all.