Levitating Cup: Anatomy of Illusion
Ok, this is straightforward. The only thing you have to do is make a tiny hole in your top hand foam cup. You can also slowly move your hands apart with your thumb firmly connected to the cup. The magician will presentably put himself before the spectators to ensure that their thumb is not very noticeable to the crowd.
Interesting magic fact: Magic has been used to proselytize. In the 19th century, St. Don Bosco was an Italian priest who was proclaimed a saint by Catholics. He used magic tricks to get kids back to school, get help, and go to church as well. This magic is now known as the magic of the Gospel.