Carbon monoxide? That's much too fancy for me, usually a good old oil rag in the mouth with duct tape applied over afterwards does the trick. Assuming of course that you've already strapped them into a chair or onto a table first. Uh..I mean...what?
Good suggestions! I've actually tried the meat cleaver one on some poor victims of frostbite. They didn't much care for it though, kept on whining and yelling at me. Saying things like "OW!" or "YOU'RE CRAZY!!" and even the occasional "I DON'T EVEN HAVE FROSTBITE!!". *shrugs* What can you do though? Can't please everyone I guess. :/