Penn and Teller Fool Us?

In the t.v show Penn and Teller Fool us , Whats the name of the trick where a guy has 4 bags and there's a piece of wood with a nail on it and its in one of the bags and the guy slams his hand on the bag without the nail in it. Please tell me because there's videos on YouTube of people doing it and it and their hand goes through the nail!