Avoid them. If they're an adult you come into contact with daily, tell someone you trust how it makes you feel when you're around them. If they're someone you come into contact with daily because you hang round with them, (your friend?) tell one of your friends that you know you can trust you feel awkward being near them. This advice is probably too late now but I thought I'd give it anyway ;D hope this helped! <3
The very first thing to do is to calm yourself down and avoid an big conflict. Next is to tell the person how you feel. If they apologize, great. If they don't, it's best to simply move on. These kinds of things can make the victim seem like the offender if you act hastily with a hurtful comment of your own.
Go away from them and inform an adult.