When people in my twitter feed make comments with no reference as to what the comments are about. This often happens during sporting events, like they will tweet "Nice play!" or "Did you see that defense!" but without indicating the game or even sport. Without any other context I have no idea what game they were even watching, so the comments make no sense. Plus I only check twitter a couple of times a day, so I'm often reading these comments 8-12 hours after whatever game it was, has gotten over. It's annoying.