Everyone has probably heard this one, but what the hell, it’s fun.
A country boy applies to Harvard and gets in. On his first day there, he gets disoriented and asks a student, “Excuse me, could you tell me where the library’s at?” The student gets rather huffy and condescendingly says, “Sir, here at Harvard we do not end a sentence with a preposition!”
So the country boy responds,
“Oh, I’m so sorry! Where’s the library at, asshole?”