A Final Exam

It was the final examination for an introductory English course at the local university. The examination was two hours long, and exam booklets were provided. The professor was very strict and told the class that any exam that was not on his desk in exactly two hours would not be accepted and the student would fail. A half hour into the exam, a student came rushing in and asked the professor for an exam booklet.
"You're not going to have time to finish this," the professor stated sarcastically as he handed the student a booklet.
"Yes I will," replied the student. He then took a seat and began writing.
After two hours, the professor called for the exams, and the students filed up and handed them in. All except the late student, who continued writing. A half hour later, the last student came up to the professor who was sitting at his desk preparing for his next class. He attempted to put his exam on the stack of exam booklets already there.
"No you don't, I'm not going to accept that. It's late." The student looked incredulous and angry.
"Do you know WHO I am?"
"No, as a matter of fact I don't," replied the professor.
"DO YOU KNOW WHO I AM?" The student asked again.
"No, and I don't care." Replied the professor with an air of superiority.
"Good," replied the student, who quickly lifted the stack of completed exams, stuffed his in the middle, and walked out of the room.