"hall monitors"

Sorry to say it but there are people like that, I know one, my father-in-law.
He has a sign on the back of his pickup "The closer you get, the slower I go", in 3 inch letters (it is a big sign).
And he does just that, no matter the traffic speed limit or the actual speed of traffic.
He also carries a can of boat air blaster (the can with a horn) that he sets off if a car with a loud stereo pulls up next to him, he keeps it in his console (he doesn't seem to realize that the person in the car or truck can't hear the  horn over the loud music).
My wife, last week, when we went out to eat, rolled down her window and shouted at a guy for texting while driving (he had wandered into our lane and jerked back into his).
I told her to just let it go, because I wasn't packing at the time and he might take offense at being yelled at by a crazy woman.
I'm just hoping see doesn't have her dad's gene for making other drivers crazy mad.