Misconceptions tick me off. They're so inherent to our nature and behavior and yet so frustrating.

I'm a bit of what one might call a grammar and/or spelling nazi, but I'm not too fanatic about it. I don't go out of my way to correct these things and do understand when people have linguistic impairments, are speaking a non-native language, are speaking in their native language just with an accent and specific lexicon and grammar principles that differ by region, make common mistakes (we all make these), etc. but otherwise, I am ticked off (exclusively) by an arguably growing lack of proper lingual skill development and "text-speak" , especially, though not necessarily by the person, just by the pitiful linguistic capabilities themselves. I edit my posts and such all the time even just for minor mistakes and that's as fanatic as it gets, so I'm not sure if I really qualify as a grammer nazi, really.
I can't think of anywhere where this really applies aside from a habit of my mother's, but she picks at food. For example, she'll dig through a brand new box of honey bunches of oat cereal with almonds... and eat all the almonds and a decent-sized amount of the clusters leaving behind some clusters and the flakes without almonds. Then she turns around and picks on me for being picky on which parts of certain meat products I do and do not eat (for example, I eat chicken and end up selectively shredding and eating various pieces so as to avoid spots I perceive as being too tough, not really chicken meat, "imperfect", etc.; meat... just gets to me... grizzle in steak, disgusting veins in chicken wings, bones in trout, etc.). I suppose that's two things in one. I eat meat, but parts of it freak me out and annoy me.
This brings me to another annoyance... hypocrisy.
Corporate/big business influence and consumerism are another one in all the facets they embody.
Another thing is my mother's habit of choking on food. I know that reads off a bit strangely, but yeah, you know those parts of chicken I avoid? My mom will try to swallow those anyway and doesn't always chew so thoroughly, so she scares me half to death every now and then when I literally think my mother might die because of how violently she seems to be choking... then she's fine a few seconds later. Still, I'm really worried about her. My younger brother used to have a similar habit and because of it and the food that typically seemed to cause it, I'm very nervous when he's eating any chewy products, particularly certain cheeses, and I myself am incredibly careful around said products, as well. Also, hard candy... hate when people eat it for a similar reason. Now that I think about it, this has kind of shown itself to be more than a pet peeve and more of a phobia of choking I seem to have... whatever, it annoys me either way.
Egotism and subsequent lack of consideration for others in reckless or selfish behavior and actions are big ones, as well. It's a broad topic, but for example, people that drive, for whatever reason, recklessly... just don't freaking do it, people and please make special care to slow the hell down in the middle of a snowstorm when other people can barely even see the road or what's ahead of them... true story.
Finally, idiots and idiotic behavior annoy me. Interpret that how you will.
I'm sure there are more, but it wouldn't do well to write all night.