People riding their bikes on the sidewalk
People riding bikes on the road is worse. Ever had one in the way when driving?

What annoys me is when my childhood gets punched in the face, and then spat on when it's down, due to capitalism. There's a million Pokemon, Nickelodeon and Disney rarely show cartoons, every cartoon has to be all happy sunshine. I watched Ren and Stimpy when I was a kid. I'm not a murderer.
Or, when people who shouldn't be famous get famous, because too many people are sheep. Just look on any music channel post 2000, and you'll understand.
Or, when people will only play a game, like a film, watch a tv series, or listen to music if it other people say it's ok.
I'll leave it at some of my top hates. I'm british, I have far too many to list.