Ron: [Harry and Ron arrive late to Transfiguration, relieved that Professor McGonagall isn't there yet] Whew, made it. Can you imagine the look on old McGonagall's face if we were late?
[the cat sitting at the head of the class suddenly transforms into her]
Ron: That was bloody brilliant!
Professor McGonagall: Well, thank you for that assessment, Mr Weasley. Perhaps it would be more useful if I were to transfigure Mr Potter and yourself into a pocket watch? That way, one of you might be on time.
Harry: We got lost.
Professor McGonagall: Then perhaps a map? I trust you don't need one to find your seats.