Joke stolen from: The Daily Dose

A college dean was berating a veteran economics professor for having used the same tests for the past 35 years.

"Don't you realize, professor, that the students have been sharing these tests for decades and that all of your students know EXACTLY what's on the test before they sit for it?"

"Doesn't matter," replied the professor. "You must realize that the subject is economics. The answers are different each year!"