Revealing mistake: When the guys go to see Tom at the BBQ, he has his head in a support cage. Every time he moves, and particularly when he laughs, this cage moves around and wobbles. The point of these cages is to keep the head still and in line with the spine, and are bolted into the bone itself. Therefore, not only should it be impossible for it to be moving, it would seriously hurt if it was.
Add timeDavid Mercier