I'll be honest and say I can understand why you blurted it out but I also understand why the people reacted this way. Telling a joke that involves religion or race can be a sensitive issue. Since my husbands family is Muslim and from the Middle East, naturally I can see how this might not be recieved well. I know you didn't intend harm though.

Just a fact - the kind of garment you're talking about is called an 'Abaya'. They're worn by many men in the Middle East by both Christians and Muslims - so this isn't a typical mosque garment.