We all have them. I have several, but some bother me more than others. Off the top of my head, the thing that makes me absolutely cringe is when people are singing along to a song and they are totally off key or don't know the words. The combination of the two can literally send me into a tizzy.
Another is typos. Especially when it's in a magazine or on a menu at a restaurant. I don't like not knowing how to spell something, so if I don't know I look it up. I wish other people did the same. I understand that sometimes it's just a mistake, but more often than not it's just laziness.
I have a bunch of others but those 2 stand out in my head. Now everybody please join in so I don't sound like an insensitive freak.