There's only ever been two times I've kicked a guy in the nuts, and both times... I didn't regret it.
The first time was the other month actually. There's this guy in our school who thinks that he can get away with hitting girls. I'd NEVER been hit, by a girl OR a guy, until then (I hate to say it but in school I'm a shameless "popular" and often seem to have my own group of grockish, enormous male "bodyguards" or so they've been called).
But anyway, I was moved for behavior in biology and sat on the "naughty table"

next to him.
He was alright with me at first actually, we'd just sit and make fun of people, have a laugh, we were pretty good mates.
And then, we were moved again, just the two of us. So we only had each other then, and he seemed to start picking on me because he had no one else to pick on.
And then after a few weeks, despite me trying to get the point across that he was 100% dick head, he actually started punching me into serious bruising and stabbing me with pens so hard it'd break the skin. Of course I yelled at him and stuff but he just found it funny.
Then, when we were walking out of lesson, he punched me full force REALLY hard right in the ovaries when I was on my period, you have NO IDEA how much that hurt along with my period cramps. I thought I was gonna pass out or throw up or both, I mean, I've never experienced it but I'm pretty sure it was like, if not worse, than being kicked in the balls. I was literally frozen with pain for about 20 seconds, before I slapped him in the face as hard as I could, then, taking the opportunity whilst he was stunned I'd hit him back, I kicked him even harder in the balls.
I seriously thought he'd ruptured my ovaries or something, I'd never been in so much pain. I was even hurting when I got home from school four hours later, I was crying with pain, I was seeing stars the whole day from the pain and considered going to hospital and stuff.
He never hit me again though, after that I requested to be moved into a different science group.
But you gotta admit, he did deserve that.
The second time was when I think I almost got raped or maybe just attacked? I was walking home through the graveyard alleyway one night, and some b***** jumped out on me, got me round the neck and waist, tried to pull me over the wall (it's only about 50cm high), then down a slope and into the trees.
I was struggling pretty frantically and the floor was muddy, so he lost balance slightly in trying to get me over the wall. In doing so I managed to struggle free a little.
Unfortunately, he still had some grip on me, so I only slid down slightly and he had his arm wrapped around my neck. I was at such a level, so as he attempted to drag me over and pull me up, I seemed to go strangely calm and my mind cleared.... I recalled this training thing I’d been on in a flash. Get the eyes, neck, crotch, shins, beneath the ribs and stomach, or slap him in the ears if things get really bad (if you do it a certain way, I think they said it pops the ear drums but it can result in death?). Obviously I went for the crotch. I grabbed his balls and squoze as hard as possible (although I could barely muster up any strength, I was too scared) until he was constricting my neck so tightly I thought I was going to pass out, and he hit me in the jaw as well.
It took him a few seconds I think to register the pain, but in that time he'd wrenched me over the wall then seemed to crumple up (that's the only way I can describe it). He tried to get me again, but seemed too disorientated.
Noting his inability to drag me any further, I screamed for help as loud as I possibly could, too scared to get up and run. Thankfully, and to this day I still thank God, three guys and two girls walked past the alley gates, and in response to my screaming ran over.
The guy, who was not only disoriented but startled by my screaming, hurried off into the trees. The group came over and got me up; we went to the police station and told them of the incident. I'd never been so hysterical in my whole life

But the worst thing is that I'm never, ever going out alone in the dark ever again. I feel unsafe, restricted, in my own city, and I hate it. Whilst everyone else can go out and meet up with friends, I have to ask them to come and get me so I KNOW I won't be alone, I have to ask to be walked home, and I feel really stupid. I haven't told anyone about the incident because I'm scared of what they'll think, and I hate that sort of attention. So they all just think I'm being a wuss.
But I HATE HATE HATE it when girls just kick guys in the balls because it's funny or over some petty reason. It's like, seriously, HELLO, you're really hurting them ! I was talking about it to some friends and they said they do it because it's like flirting. I was like NO IT'S NOT FREAKIN FLIRTING, you're really hurting him, you could really harm him ! The sad thing is though that the guys they do it to seem to think that they (the girl who kick em in the nuts) are doing it because they're kinky or trying to flirt ! I mean if I was a guy and some girl kicked me in the balls coz she thought she was being sexy, I'd F****** go crazy on her (wouldn't hit her back, mind).