I think it's actually important to recognize that a woman is engaging in pathological masculine behaviors.

It's a way of saying: "That's unmanly" and "That's not ladylike" in modern speak because those phrases have been attacked to the point where standing against them is somehow a good thing.

Not only are you acting like an asshole, you are acting like an asshole of the opposite sex, which shows just how fucked up you are.

Really, the same thing is happening when you call a man "a bitch".