Female-on-male violence is viewed as more acceptable in fiction than male-on-female violence. Often, a woman using physical violence on a man will be Played for Laughs; sometimes it will be Disproportionate Retribution. The key is that in most works where this trope is in effect, it would be completely impossible to imagine the same violent situation play out with the participants' genders reversed without a large dose of drama getting added into the mix. The basic Double Standard at work in this trope is sexist on both sides: no woman is strong enough to harm a man, so any man weak enough to be harmed by a woman isn't a real man, and that's funny.