Hardcore feminist women are sometimes over-senstive. They are also more angry than most people because of the perceived injustices, even if they are legitmate. So in their interactions with men, a very little slight will give the already angry, over-sensitive feminist a reason to hate the man. The feminist will come away from the situation believing that her hatred of that man is not arbitrary and that rather, there was a good reason behind it. But in reality, she is probably being over-sensitive and judging the man over something petty.
This probably applies to a smaller percentage of feminists, but that probably where the stereotype comes from.
Here's an anti-ridiculous feminist song!
When they said "sit down", I stood up.