I think it was “you look like a woman”, and sometimes people don’t want to be told they look like the opposite gender they identify as. ( ̄∇ ̄")
Idk if it’s sexism as much as it’s “knowing exactly what to say to piss you off”
Bro just doesn’t want to look like a woman, so it was used as a means to insult him
Again you try to explain the obvious.
He said it because the guy was complaining, as if complaining is what women do. That he has long hair and dark lips might have further inclined him because of his likeness with popularised and typical feminine traits. But the "insult" was still a response to his complaining, which makes it a sexist remark.
"Woman"...?