Harvard's manners

I remember I read once in the local newspaper of Raleigh, N.C., The News & Observer, about somebody who was lost in the Harvard University’s campus looking for the library. After some minutes of fruitless search, he decided to stop his car and asked somebody walking outside:

- Excuse me, would you please tell me where the library is located at?

The astonished pedestrian reacted with surprise and anger to this question:

- Excuse me you, sir, I don’t understand; here, in Harvard, we never end a sentence with a preposition.

- Oh!, I’m very sorry, would you please tell me where the library is located at, son of a bitch?