When Strangers Give Offensive Greetings, For No Reason

I find it very strange when you are sitting at a stop light in town minding your own business, when a stranger parked in a car to the left is pulling out and as he gets next to your window says "a**hole". I didn't get in the guy's way or do anything offensive and I didn't even know the person. Yeah, well f*ck you too buddy!