Crazy Chris shows us how to make a cool boomerang out of two Styrofoam cups - useful as a party trick. Plastic and paper cups can also be used. The bottoms of the cups are taped together. The key to making the boomerang work is the positioning of the fingers on the cups. The middle finger should be placed in the middle joint of the two cups - the fingernail in contact with the tape. The pointer and ring fingers should support the top of the cups and the thumb gives the bottom support. Chris then flicks the cup-boomerang with his middle finger. It moves up and away before returning back to him. He catches it. In the final part, he explains how the boomerang works. In flicking the cups, a spin is created making a low pressure area on one side. The high pressure on the other side pushes the cups back and Chris is then able to catch cup-boomerang.