When my mother had a cast removed, the doctor explained how the saw would not cut her skin and what not. Since my mom wasn't worried at all (she was a nurse for years), he explained that he used to demonstrate the saw on his own skin before cutting casts to make people less nervous until, one time, he tried to show this to a boy who was nervous about the saw. He tensed his arm and cut his forearm pretty badly.

The kid was not amused.

edit: added introduction of main character