Hypnosis Question and theory help please.?

Why is it that when people get hypnotized they take off their shoes? In all the shows that I have seen they usually do it after they have gone under, so it can't be a comfort thing. So why do you think they do it? Most of the people you see doing it are pretty girls with pretty painted toenails, and they usually do it while deeply asleep and under. I'm thinking the hypnotist might have a bit of a foot and if he notices a girl who might have cute feet (or if she has flips on and he can tell she does) he might put that suggestion in her head that she take off the shoes. What do you think?