May be you have been speaking without consideration and giving a chance to others to laugh at you. Otherwise those 'some' people would befriends to each other and don’t think that Allah says in Quran "O people who believe, your males never make of other males and your females never make fun of other females, may be they are better than them." The people of Makkah used to make fun of our beloved Prophet Muhammad (peace be upon him) but he never overreacted. He tolerated their behaviour. However, if they start bullying you, tell your teachers so that they could handle the issue.