The college had a very good football team, and its best player was a student who always had trouble in school.  Then one year the dean of the college said that the player had to leave because he had cheated on an exam.  The football coach immediately went to the professor to try to persuade him to let this student stay in school.  The professor  showed him two answer papers.  “This one is Susan 's paper.  She's the best student in the class,” he said.  “And this one is your football player's.  They're exactly the same.  The football player sat at the next desk, and just copied from her.”  “But maybe she copied from him,” the coach said. “You can't prove it was the other way.”  “Look at this,” the professor said.  “Susan didn't know the answer to this question, so she wrote I don't know.  And your football player wrote, Neither do I.”