You're a prefect? Oh Ronnie! That's everyone in the family!"... - J.K. Rowling, Harry Potter and the Order of the Phoenix

"From now on, I don't care if my tea leaves spell 'Die, Ron, Die,' I'm chucking them in the bin where they belong."

"Well, we were always going to fail that one,"said Ron gloomily as they ascended the marble staircase. He had just made Harry feel rather better by telling him how he told the examiner in detail about the ugly man with a wart on his nose in the crystal ball, only to look up and realize he had been describing the examiner's reflection."

"Accio Brain!"

"My Head of House said I lacked certain necessary qualities...like the ability to behave myself."

"Yeah, Quirrell was a great teacher. There was just that minor drawback of him having Lord Voldemort sticking out of the back of his head!"