I got the same comment yelled at me from a passing car (oddly enough, it was in Chambersburg, PA). The best thing to do in those situations is to just ignore it. I've also had guys tell me how great it is that I was wearing a kilt. And not just any guys, I'm talking biker types, body builders, etc. I've also noticed an increase in the attention of attractive ladies when wearing the kilt, so I don't really care what the idiots yell from a distance.