Legal vs Logical ? (Humour)

After having failed his exam in "Logistics and Organization", Johnny goes and confronts his lecturer about it.

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

Professor: Surely I must ,otherwise I would not be a professor !

Johnny: Great, well then I would like to ask you a question.. If you can give me the correct answer , I will accept my mark as is and go.. If you however do not know the answer , I want you give me an "A" for the exam.

Professor: Okay, it's a deal. So what is the question ?

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

Even after some long and hard consideration , the professor could not give Johnny an answer , and therefore changes his exam mark into an "A", as agreed.

Still puzzled , the professor later calls on his best student in his class , Sihle , and asks him the same question.

Sihle immediately answers , "Sir , you see , 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. The fact that you have given your wife's lover an "A", although he really should have failed , is neither legal nor logical."

The professor fainted!