Today my friends were treated unfairly by that Mean Teacher Assistant, what should I do?

Okay well first one of them were wearing sweat pants and when That Mean Teacher Assistant saw that he said "HEY! YOU'RE NOT SUPPOSED TO BE WEARING THOSE! GO BACK TO THE CLASS YOU WERR GOING TO AND TAKE THOSE OFF YOU IDIOT!" and then He goit mad and went away to do what the Rotten Douchebag said.And then he yelled at someone and said they weren't Aloud to go back to his room and threatened him.I am honestly tired of these teachers being such a-holes.What should I do?