Drama in class

Tuesday, yesterday a girl got called a pig by my mathematics teacher, are they even allowed to do that? Though she was being disrespectful to the teacher, the girl is kind of a slob too, but in reply to what my teacher called her, she literally said "take a step back like your hairline" Some of the boys laughed about it, but the girl got detention and the teacher seemed pretty pissed off after that... to be honest it was funny in the moment but the man is 65 years old, he cant control that.