I would like to help my friend by making her understand not to listen or bother what her classmate say. Let them say what they want.They like to see you getting hurt and irritated . And because you react . they do more.SO JUST STOP GIVING ATTENTION TO THEM AND IGNORE THEM.they will ultimately stop teasing you.
And if the matter goes above head , then i will have to address it to the principal and her parents .AND the principal will take steps against those people.