I wonder what I would do if someone told me they were some sort of gender freak and gave me they/them pronouns or something similar.
I think it would depend on the context and if it was safe to insult them. I would like to insult them, but if they were someone you would have to see all the time, or if you would get in trouble at school or work, or if insulting them would embarrass a friend or family member of yours, you might have to bite your tongue.