The Reverse Beartrap in Saw 1

I like this trap.This trap was applied to a heroin addict named Amanda Young, whose wrists were bound with duct tape to armrests on a chair in a dimly-lit room with a heavy metal apparatus hooked into her upper and lower jaw. The Jigsaw Puppet appeared on a television screen before her and revealed that Amanda had a short amount of time to remove the trap from her head before it would snap open like a bear trap in reverse, which would rip her jaws wide open in the process. To emphasize the point, a demonstration was shown to Amanda, who watched as the device went off on a mannequin head, which exploded as the device activated. The puppet told her that the key that she needed to remove the device was in the stomach of the "dead" Donnie Greco lying across the room from her.
As the tape ended, Amanda was forced to wriggle her arms free from the duct tape, at which point she stood up, pulling and snapping a trigger wire that set off the one-minute timer on the back of the contraption on her head. She quickly raced over to Donnie, whereupon she had to cut into his stomach and retrieve the key, although it was revealed that he was not actually dead as the tape had suggested, but in an opiate-induced state of paralysis, unable to feel pain. He began stirring and eventually woke up as Amanda cut into his stomach with a scalpel and retrieved the key. Amanda managed to remove the device just in time, grabbing it from her head and tossing it to the floor as it snapped open.