I am reminded of an anecdote told to me my first year of college at the University of Illinois (student population of nearly 40,000). I have my doubts about its truthfulness, more likely it is a common urban legend and told at every school of 20,000 students or more. Nonetheless it is humorous and entirely plausible.
The scene opens in a lecture hall of about one or two hundred. This size of class was the norm at my school, especially in the first year. It is the last day of finals and the professor has handed out all relevant test materials. He then informs the class that they will have exactly three hours to complete the exam, and not a second longer. "I will not accept any exam after three hours have elapsed, no matter what the circumstances," he tells them.
After about two hours, students start finishing. First in ones and twos, then dozens. As the three hour mark approaches, with warnings given by the professor, only a handful of students are taking the test. They all finish in the last few minutes and hand in their exam save one. "The exam is now over, I will not accept any more answer sheets," the professor announces. He picks up the stack of exams and begins to walk out the door.
"Hold up, professor!" the last student says. He marks down one or two more answers then rushes up to hand in his exam.
"I'm sorry, but I can't accept that," the professor tells him. "You'll have to take a failing grade for the exam."
The student looks the professor in the eye and holds his exam up in a menacing fashion. "Do you know who I am? Do you have any idea who you're up against?"
The professor could give two shits who this kid is, he's not taking any late exams. "No," he says. "I have no idea who you are."
"Good," says the student. He shoves the pile of exams out of his professors hands and they spread out all over the floor. He then slips his underneath the pile and high tails it out of there. The professor can't figure out which exam is the late one, and is forced to grade them all.
P.S. Scribe points out the 2002 movie Slackers, in which a similar scene took place, while Professor_Pi points to the Snopes article, suggesting a much earlier source.