I've tried to stay out of this one because usually when I get started, I can't stop, but ...
A lot of mine are about driving because I do so much of it! I HATE people who don't signal! On my way home, I go up the exit ramp of the interstate and then have to turn left on to a busy State road and go over the bridge that's the overpass for the interstate. To the right is a busy truck stop with lots of vehicles leaving to get back on the interstate. So I'm sitting there and I could turn left but then there's a vehicle coming from the right and since they're not signalling, I have to assume that they're going straight ... so I sit there. And almost every time they will turn right on to the interstate without signalling ... and I'm still sitting there, and I could have turned! But by then there's something coming from the other direction and I'm waiting again!
And I hate having one of those people in front of me who finds it necessary to put their blinker on when the person in front of them is signalling to turn! What's with that anyway? You're behind them and they're signalling and you expect them to turn - then the person in front of them turns, and they don't! I have a friend at work who does this and she thinks she's helping ... she's not!
And don't even get me started on the cell phones, especially people who are off in their own little world jabbering, eyes glazed over, while they're driving! I just want to slap them! I'd be willing to bet that 99% of the conversations are completely unnecessary. And in the grocery store ... I can understand answering it if it rings, especially if you're waiting for a call. But I really don't like to be forced to listen to people's private conversations in the cereal aisle! And so many of them seem to be these mindless, pointless, stupid conversations like, "What are you doing? Nothing. What are you doing? Nothing ... " I don't make those kinds of phone calls and I sure don't want to listen to someone else's! And people will talk about the most private things, like their trip to the gynocologist, oblivious to the dozens of people who are close enough to hear them. Then they give YOU a dirty look, like you invaded their privacy! Sheeesh!