1) Telling a feminazi that she is wrong (doesn't matter how right you are or how many facts you present). They will then say you are sexist and that you are "mansplaining"
2) The concept that men will talk down to women just for being women (total bullshit in most cases).
Feminazi 1 - "Oh my god, Bob tried to tell me that some men are good people."
Feminazi 2 - "He was mansplaining. All men are pigs, remember that"
Unsure person - "Do men mansplain a lot? I've heard it before but I'm not certain if it's true or not."
Reasonable person - "No, almost no men mansplain. Most cases, the woman is unable to accept that she is wrong so just says she is mansplaining. Sometimes, the man is just a prick. He's not sexist, he's just not a nice person.