It never seems to end. Many of these same people would never buy a Muslim co-worker a new "Towel" for her head.

Would they make fun of any other national style of dress to the wearer's face? Why is it we live in a society that sees to think that it is okay to mock another culture?

This situation as described is the very definition of a hostile work environment. HR should have something to say about it.

The fact that it took place in front of your students makes it even worse. If your co-workers can not treat you with respect while in the presence of you students, how can the students be expected to treat you with respect.

I feel that you must demand respect from your co-worker. If they can not deliver, then you must take things to the higher level and file a formal complaint.