You're a brave person asking this place for advice....
Unfortunately too few of us take the time to familiarize ourselves with other's customs. I've noticed the different shapes and sizes of turbans and other head gear but have never asked anyone outright the differences. If you tried to explain and he still remained an ass maybe you should seek advice of the HR people in your company. Making fun of the turban is a form of Religious/Ethnic harrassment.
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Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming ...."WOW! What a ride!!!!!"
LUNCH with THEOLDMAN...On a break for now...