Seriously?
However, if there are no 'rules' in a street fight, the shortest most direct point to pain would be a front kick to the shin.
I'm not sure its allowed in K-1 / MMA type fights, so maybe you aren't taught it, but a kick to the shin can break it and end the fight right there, just imagine the scene; 2 fighters square off a la boxing style, then one shoots a low front kick to the shin...and remember he has boots on. There's no need to telegraph the kick like a thigh shot, which at best is likely to dead leg the opponent and at worse get caught leaving you in trouble.
Knee shot? sure, same result as the shin, but higher, so slightly slower and easier to read.
Military combat can fill in the dirty holes that martial arts can't.![]()
A kick to the shin would be perfectly legal in both MMA and K1. How you can say you have studied martial arts for 24 years and not know this is rather.... surprising.