I couldn't get a picture of this one. Too bad because it would've been good!
That is one of the most legally rude things you can do without actually saying something. I was beaten up in junior high over a mistaken finger gesture made by my best friend. (I don't recall how I became the protector.)
Driving down a country road, passing a tractor, seeing someone at their mail box, you politely lift your pointer finger off of the steering wheel and gesture, "Hello." Am I right?! Oh, I think there is a slight nod of the head.
Another win for Mississippi, the hospitality state.