I don't know if this story is real but I will tell it as it was told to me:
On a philosophy exam the teacher had put only one question (not really a question as you'll soon see): "Prove to me that the chair I am sitting on doesn't exist." All students went to write long essays about existencialism and it being dependent on the observer, questioning the observer's existence the usual philosophical yadda yadda yadda. When the exam was corrected the top mark was given to a student and his/her answer was: "What chair?"
Can't say I didn't love this story. 🙂