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.
In russian if you cry you get called a cabbage. Vote to change “dont be such a girl to “dont be such a cabbage” say I.
sometimes, NO sounds like “umm”.
sometimes NO is the holding of a breath.
sometimes NO is screamed through a facial expression rather than a verbal negative.
sometimes NO is in the dead stare of someone’s eyes.
sometimes NO is in the back of our throat when we answer “Yes.”
sometimes NO is obvious to us but invisible to you.
NO is not always verbal. communication isn’t always that easy.