The day before exams, four college roommates decided to stay up late drinking. Needless to say, they were late for class the next morning. But they thought they had a good alibi.
"We blew a tire on the way here," said one of them.
"OK," said the professor, "but you will have to take a different version of the exam than the other students."
The first question, worth 95 points, read: "Which tire did you blow?"