Holly B.

Here is great video clip of Kelly McCann explaining the Chin Jab.

Some downplay its effectiveness, but they thought it was effective enough to teach it to soldiers in WWII. The technique is explained in detail in W.E. Fairbairn's book "Get Tough".

Here is my old post on the Chin Jab technique from Gutterfighing USA. http://gutterfightingusa.wordpress.com/2009/05/07/chn-jab/