Telling your son not to “be such a girl” lets his sister who overhears the conversation know that being a girl is not a good thing and she should be sorry and ashamed of herself.
It also reminds your son that being a boy is better than being a girl and therefore he is better than any girl he will ever meet.
One time this girl I know posted on facebook that she wanted donuts and more than one guy brought donuts to her house. That’s my dream.
this is actually the literal dream