September started some days ago, and there's always something that comes along with that - thousands of people on twitter with the hashtag #WakeMeUpWhenSeptemberEnds, and with thousands complaining about that fact too.
Why does this happen?
Wake Me Up When September Ends is a Green Day song, which was written by Billie Joe Armstrong (singer of Green Day) talking about his feelings towards his father's death. Billie was 10, and after the funeral he ran away to his room and lay in bed, when his mother came looking for him, he said: "wake me up when September ends".
Most people who write tweets saying "wake me up when September ends", only say it because it's when school starts, which is why it annoys many people - the truth behind that line is way harder than that and it's not something to joke about.