Student: "Sir, do you really understand anything about the subject?"

Professor: "Surely I must. Otherwise I would not be a professor!"

Student: "Great, well then I would like to ask you a question. If you can give me the correct answer, I will accept my marks as they are and go. If you do'nt, I want you give me an "A" for the exam. "

Professor: "Okay, sounds reasonable. So, what is the question?"

Student: "What is legal but not logical, logical but not legal, and neither logical nor legal?"

Even after some long and hard thought, the professor cannot figure out the answer and, therefore, changes his exam marks to an "A", as agreed.

Afterwards, the professor calls on his best student and asks him the same question.

He immediately answers: "It's quite simple, Sir. You are 63 years old and married to a 35 year old woman, which is legal but not logical. Your wife has a 25 year old lover which is logical but not legal. That you have given your wife's lover an "A" when he really should have failed, is neither legal nor logical!"