IMO, any technique that "relies" upon the groin shot should not be considered reliable. Many people are impervious to pain in a street fight for various reasons. Some people even wear groin cups. Have some other form of technique that isn't based on a person "deciding" to quit holding you in a headlock (or any other position/situation for that matter).
i completly disagree, and i have never met anyone who is impervious to being smacked in the nuts. krav teaches more than one way to get out of a headlock anyway. and sorry to hear about you getting jumped man that seriously sucks.