It really bugs me when people don't even try to use proper grammar.
As far as the road goes, turn signals are a big peeve. But that goes for a lot of people. I'm also frequently bothered by people who don't seem to get the concept of the acceleration/deceleration lane on the highways. You are trying to merge with a traffic going 70mph, and then there is some asshole in front of you who can't find his accelerator pedal.
Speaking of speeds on the highway, I can completely understand if you're not in a hurry and are holding 65-70 in the 70mph zone. I also understand that some people don't care much about fines and really need to get somewhere, so they go 65-70 while going through a 50mph construction zone. But if it's you in both cases, you're just an asshole. If you really have somewhere to be and you don't care about being pulled over, do your 80-85 in 70 as well. And if you're not in the hurry, or you aren't feeling confident driving 80-85 on a clear road, the slow the f*ck down in construction zone.