Well... perhaps it's the well-hidden sadistic nature in some of us, and some find it amusing seeing other people in pain. I think kicking a guy in the nuts in particular though is perhaps not taken as seriously as it should be, I've heard many, many, many guys complain about this, and I think girls doing it and finding it funny perhaps stems from the fact that we don't know what it feels like, and we don't have the same genitals! But generally if a girl does it for no reason AT ALL, other than to have a laugh, well, honestly it sounds a bit (okay very) crazy!
I agree that the only time this is acceptable is in self-defense.
The only reason I would do that on purpose is if I was being attacked. That's what you're taught in self-defense classes. Are you seeing roving packs of women running around and kicking men in the testicles or something?
I've never seen or heard of anyone actually do that in real life... I assumed it was something only used in self defense or happened on accident. That's messed up if a girl just does that for any other reason. We've all heard how badly it hurts men to the point where men debate whether it parallels birth pain. So many nerve endings!
It's not funny and whomever did it to you recklessly endangered you and you need to stay away from them. If this not self defense on her part then you were the victim of an assault. Not sure what your legal rights are at this point, however.
well, it depends in what kind of situation you do it xD I personally haven't ever kicked a guy in the nuts, but if I'd have a boyfriend and I would see him kissing another girl, I'd probably kick him in the nuts ':D