That isn't quite as bad doing that to a pickup truck, as it is an 18 wheeler. They pull that crap with us too. It isn't an uncommon event either. If not nearly every day in a city, it happens every week. week. #@$%! #@$%! Not always to me, but I see it happen to other plenty.
I don't use the horns much, but I did have to do it 3 days in a row, a month or 2 ago. Got brake checked twice, and had someone pull right in front of me.
They don't understand I'll win the fight with the car. 80k vs 3-5k. Hmmmmm. I wonder who will win.
Most don't even "look" so there for it isn't there.
In my neighborhood we have un-controlled intersections. No one slows to what I feel is a max of 10mph to safely check right and left twice to ensure safe passage.
This "ghetto fabulous" punk in his POS car didn't realize that I'm slowing to a crawl and in the middle of the road with my right blinker on FOR A REASON. as I need to make a semi-wide turn to get into my spot in my driveway.
Knowing the typical patterns of ppl in the area I kept and eye on the mirrors. And wouldn't you know it, As I'm about to TURN he PASSED ME on the right squeezes between me and the curb.
I forgot, your a thug, you don't have to wait for traffic to clear. Sorry My bad. Red lights are optional as well. The guy didn't look, didn't turn his head didn't get up from his lean. nothing. I laid on the horn and started to turn to see if I can get a reaction. nothing.
It would of been pre-meditated "something" had I just hit the guy. I could of done some serious damage to his coke can of a car and him. I'm and a-hole, but I do have my lines if I can advoid it I will.
Now a train horn, that would of gotten some attention.
In the end, I took a walk, found out exactly what house he lives at (3 blocks away). Talked to a cop on detail by the park and he promised to visit the guy.
Attention: TDR Forum Junkies 
)
