People who tell you to do something in a specific way, then get mad when you do it in a specific way.
People who argue with their age.
People who touch your stuff without permission. (Don't you dare search up random "potato pe**s" on my laptop while I'm in the toilet)
EDIT: Spotify ads. I mean, I get putting ads after the first song and after several songs, but do they HAVE to be the same ad?
When there's a spammer on the boards but there are no mods on.