Hurt most - crotch..
Knockout - an uppercut to the jaw.
Either will likely result in criminal prosecution if not inarguably self defence.
Edit - note that being 'knocked out' is a result of trauma (injury) to the brain, and anything that does this has a chance of causing permanent brain damage. It is not something to be taken lightly.
I think it is either at the base of the jaw or the pterion, the latter is the technical term for the thin parr of he skull, the jaw is more painful in the long term but the pterion can cause excessive damage to the brain if hit too hard.
if its a man just kick them so even their grandkids will feel it, if he can still have them of course,
I don't know about knocking people out but hitting a male in the nuts or someone in the throat would be pretty painful in my opinion.
In the balls right after an operation to cure testicular torsion, which was caused by extreme sun burn.
To answer your question the sorest place to be punched is in a nice pair of extremely sun burnt testicular torsion suffering balls.
The liver.
Feels like someone took out a knife and carved you up when nailed down there. The pain is so much it paralyzes you for about 30 seconds.
The side of there face or possible the side of their chest
Where can I hit them that will hurt them the most ? And don't give me any of this "violence isn't the answer" , I'm just wondering.
Also where can I hit someone that will be the most likely to knock them out ?