Inverted Neck Break

The Inverted Neck Break or INB is a special athletic move widely seen in Playstation 2 video game, Splinter Cell: Chaos Theory and executed by Sam Fisher. The move is not a fictional move that Sam Fisher executes. In fact, it is widely used by the Israel Defense Force as a extremely difficult manuever which is based around stealth. On clandestine intelligence-gathering missions, operatives probably have to infiltrate an enemy building. If there are enemy guards present, Defense Force soldiers must approach the enemy from a very unconventional angle. And that angle is hanging upside down and breaking the cervical vertebrae which kills an enemy instantaneously.

What The Inverted Neck Break Actually Is
The Inverted Neck Break is literally hanging upside down from a horizontal pipe/rope, with the legs tucked. When an enemy soldier nears your position, you quickly grab the enemy's neck and break the cervical vertebrae by popping the neck up and forward. Doing all this, you must have the balance of still hang on the horizontal rope/pipe without falling off and ruining your stealth kill. It the game Splinter Cell: Chaos Theory, it is actually a difficult maneuver.