I would not take things like this personal. Personally If someone makes fun of me I can be sure they make fun of other people too. Which I would not accept. It says a lot about their character, what you do with that information is entirely up to you. It sucks they are your co workers, I guess you have to interact with them. If you think they are mature enough you can talk to them about it in a nice way. I don't know your work situation. If it doesn't work you could go to HR or bring the problem to the supervisor.