I'm not saying NEVER used it...but just don't RELY on a kick to the groin....it is hard to hit in a fluid environment....takes a few seconds to affect (during which you could be stabbed and in 5 he's fine and u have a new hole in your body)...and its mostly pain (you do not know his threshold or if he can even feel pain...like if he is on drugs)....so don't rely on a groin kick...
Your primary targets are: Eyes and Throat!

Also pepper spray and mace...while they will affect MOST people, do not rely on them either (key word is most)...had a bouncer friend who got hit with it once and decided he wanted to build up immunity to it...he sprayed himself daily and is now IMMUNE to it...so don't rely on it either.

Awarenes is your first line of defense...and never EVER dismiss your instinct if you feel something is up....90% of rape victims interviewed said they sensed something was wrong before the attack but dismissed it!

If you can...enroll in some certified self defense (or better yet as it is more focused) Rape prevention seminars or courses....I know it can be pricey but think about this: people will spend tons of cash on dancing lessons, but this MAY potentially save your life!

Stay safe all.

Perfection does not exist. The question therefore, is: what level of imperfection are we willing to settle for?