The Comedian's Trap

A comedian would have his head in a large leather ballon, mixed with part of a beathing mask. After hearing his tape, he learns that helium will be pumped into the balloon, which will eventually kill him due to lack of oxygen. To escape, there's a box with a blade inside it attached to a lever. He has to press hard enough against it using his hands, because the box is too tight for his balloon to pass through. If he pushes far enough, the box will open, and he can use the nice to cut open his mask and tear it off.