Not a whole lot aggravates me or gets under my skin, but a general lack of work ethic has been getting to me lately.
Being in the military I see a lot of this (yes, I know there are lazy people everywhere). We all have our fair share of stupid shit we have to do, usually on top of normal work, but I cannot stand the people who put more effort into getting out of work or doing the least work, than actually just getting the job done and helping everyone out.
For educational purposes, if you didn't know, the American military gets paid every two weeks, no matter what, and the pay is constant, not matter if you worked 120 hours a week or 20, a two-edged sword. Thus, I run into a good amount of soldiers who, knowing they're getting paid anyway, seek to get out of the work that everyone else is just sucking it up and doing, even if its their day to day job. Whats worse is the superiors who fail to notice this. I show up to work on time every day, I do my job without bitching, and when stupid stuff comes up, knock it out and move on, yet because I'm reliable, I often work long shifts, pull call and am made to come in on my days off to cover down for someone with the above mentioned attitude. And guess what? We get the same pay...
TL;DR: people who think they deserve the pay they get while doing their best to avoid actually earning it.