obnoxious, supercilious people who are vocabulary or grammar nazi's on an international message board.....really? Grow up.
People dissing on my "biggest little city"; I LOVE where I live, and everything around us. You don't like it, you haven't been out and about enough, or you're just a grump.
Tardiness. I'm like my dad in this, and maybe it was us both being in the military. While I don't take things personally (because really, who needs that? it's like seeking to be offended), I think tardiness is a disrespect of ME and MY time. (especially at work when I have been there 13 hours and am wanting to get home to bed)
People who are mean to other people, children, and especially animals. Does that make YOU a big, important person? Whatever.
People bringing politics, religion, or squicky personal life details out at work. Again, maybe it is the reserved and regimented military background, or maybe it's just being a grownup!

But in my mind, those things just don't belong there.
Bad drivers, bad language in public, and bad breath at any time!

Gum or mints are cheap, folks!
The stench of cigarettes. I'm allergic to smoke, which causes issues when we have wildfires in the area; I get wickedly nauseated and break out in hives. So when I am taking an elevator and a heavy smoker gets in, it makes me queasy. They may be a wonderful person, and I don't judge the person based on their habit, it just makes me physically ill to be around it.