Freshman year at the University of Arizona, in my Sociology 101 lecture. I was seated next to two very pretty girls. Unfortunately, that Sociology 101 class was pretty deadly dull.
I started taking notes, dutifully, but Morpheus got the better of me. Next thing I knew, I was jerking awake as everyone around me got up to leave. Confused, I took stock of the situation, and realized I'd continued taking notes after losing consciousness, but moved off the paper, and my left arm was now covered in angry red welts and deep blue ink.
Checking my notes (on the paper) later, they went from the standard verbatim transcript of what the professor was saying into what appeared to be a short story about meeting Ozzy Osbourne at a 7-11.