Yeahh, the couch thing is annoying if you don't like them or know them as good friends.
Me personally? When someone stalks you just to be a troll. And they won't stop. And their name is something ridiculous in all caps like PICKLES or something. Their pelts are always neon and they wear ugly accessories....
Also I find photobombing irritating, or what I've seen a lot of is when I'm trying to make a video clip that's dead serious someone's holding down the spacebar and jumping up and down nonstop behind me and making my video look bad.
But, I'm not easily annoyed. I feel like I have a good amount of patience with younger kids..