Try not to listen to your friend’s wording. We live in a society where some people make some beauty/body standards for men. But you don’t need to be worried about it. Your short height doesn’t make you any less of a man. Try to ignore them as much as possible. And if they bully you more, then talk to your parents about this. Later, you can file a complaint against them to your class teacher. And if he refused to take any action then you can directly complain to the principal.