People who drive and constantly have to have that cellphone glued to their ears.
I followed a woman into work last month who is always talking on that phone. I've unfortunately been behind her on numerous occasions. And she is all over the place. As you enter the parking lot they have those reflector markers along the road as you turn in. She took out a whole row of them as she was turning and never blinked an eye or knew she did it. I just laughed.
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"Hey idiot! You can make a right turn on red in this state!"
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Leaving the turn signal on. I tell my kids they are making a left turn around the world.
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Driving through (or across) parking lots and not using the lanes. It's like being in a demolition derby.
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I work 3rd shift. So on occasion I'll stop at WalMart on the way home when there is no one there and the parking lot is pretty barren. I'll pull in and park my car, and when I come out some idiot has not only parked his car right next to mine, but has parked so close that I can't even get my car door open. The whole friggin' parking lot is empty and they had to park right next to me?