You were trying to sleep, you were the Quidditch Professor, the favorite Professor of Oliver Wood because you make him learn new things in Quidditch and you were a young Professor, you were only 19 years old and you were a boy.

And you were really trying to sleep but you heard the Gryffindor boys being stupid and singing in the Gryffindor common room.

So you decided to go in the Gryffindor common room and you saw Harry, Fred, George, Oliver, Percy, Ron and Neville singing "Call Me Maybe" but they were drunk, they were all drunk so they were singing loudly with the song in the background.

You were standing by the doorway of the Gryffindor common room and you were in your Professor pyjamas clad and your mouth agape because of the drunk boys in front of you, you never saw Oliver and Percy drunk like that, the Gryffindor Quidditch Captain and Gryffindor Prefect..

And that's how they greet their Quidditch Professor, polite..