As a sophomore in college, I took a medical sociology course. A research paper was a major part of the grade. On the last day of class, the professor passed out all the graded papers, except for mine. He announced: "Mr. Schulin, please see me after class." When I came to him, he said "I don't know where you plagiarized your paper from, but this far exceeds what an undergraduate could produce. You get an F for the paper and for the class." I smiled and said "Dr. Tavani, I'm glad to hear you say this exceeds your expectations for any undergraduate, because I'm sure that after I show you my research file, you will have no doubt that I wrote this paper myself. I expect nothing less than a A." He agreed to wait for an hour while I drove home and retrieved my 4x6 card fileboxes. I ended up getting the only A in the class.
I didn't begrudge my professor's initial poor opinion of me. I was delighted to learn that I exceeded his expectation of what was possible.