Mistwell
Crusty Old Meatwad
Yep.
It goes something like this:
"Oh you're a gamer eh? You like D&D? Well who was the king of the dwarves in the Forgotten Realms in DR 1050? Oh you don't know? Fake gamer girl."
But it happens directed at new men to the hobby as well. Which is why I say this claim it's about women is baloney. I don't think there is a correlation. And I have seen lots of people behave poorly towards women in gaming through role playing as opposed to through rules gatekeeping. I think we've all cringed as we saw someone try and hit on a girl through the role playing in the game. And then there is just plain direct sexism to the woman, unrelated to gaming rules or role playing just in the room out of character. I see no correlation between those who gatekeep using the rules, and those who behave that way to women. It's no more or less common as far as I can tell than other forms of bad behavior towards women in gaming.
I think some don't like rules gatekeeping, and also don't like sexism, and are connecting the two out of an assumption that what they perceive as bad behavior #1 is connected to bad behavior #2. I don't think they are connected (any more or less than "people who behavior bad at one endeavor tend to behave bad in other endeavors").