I totally get it that it is the cultural norm for boys to have short hair and girls to have long, but isn’t a set rule. There are so many boys with long hair and girls with short. The assumption that my long-haired boy is a girl is a tad annoying. It would be so nice if the English language had a gender neutral pronoun for when you don’t know someone.
My tactic for handling short interactions with strangers is to just use he in my responses. For longer term things, I make sure they know. For example, here’s what happened when we went to the police station to pay my parking ticket (I parked on the street overnight because I was too sick to shovel the driveway and couldn’t get up it with the 6in of snow we had gotten, there are no signs on the street).
Officer: would she like a sucker?
Me: thank you, but he doesn’t know how to eat them.
Officer: oh, well that’s probably best that she can’t. (insert chuckle)
Me: yeh, he just gets mad that he he can’t chew them.
Boys can have pretty hair, too!