I've had a few good ones:
In college I got a paper back with "near-perfect paper!" written on it. I found this particularly amusing since the paper was an essay on the aesthetics of home-made bong construction. (
Here if anyone's interested)
In a high school math class I once was called on to solve a problem on the board. I went up to the board with my disc-man and headphones on, listening to music while solving the problem. One of the other students complained, "You always tell me to turn off my music! Why does Mike get to wear headphones?" To which the teacher replied, "When you get perfect scores on all the quizzes, you can listen to music in class, too."
In my 11th grade English class I turned in a paper on the use of music in Ralph Ellison's
Invisible Man. Afterwards the teacher asked to talk to me in the hall. She asked me if I had any help writing the paper, like from my parents. I said no (true). She asked if I used any study aids, like Cliff Notes. I said no (again, true). She said, "You know what this means, right?" I looked at her, figured out what she was getting at, and said something along the lines of "Oh, crap." To which she replied "Yeah, I'm going to be expecting work of this level from you from now on." Her estimation of me raised considerably right there, and she pushed me
much harder the rest of the year. Of course, I wrote the paper in question in one long sitting the night before turning it in. So it goes.