Another (shorter) one from 6th year Physics
The head of department was taking us for a class.

He was writing some formulae on the board, and we were dutifully copying them down into our folders.

As the work continued down the board, I felt obliged to ask a question regarding his derivations.

"Sir, I can see how you get from the 2nd line to the 3rd line, but how do you derive the 4th line from the 3rd?"

He fixed me with a stare that would melt carbon.

"Because it says so in my notes", he explained.

Well that explains that then. And they wondered why we weren't interested....
(Reverend Fister "a disciplined fuckwit", Tue 3 Feb 2009, 11:24, Reply)