My major in college for my BS included all but 2 credit hours of a physics minor, so my final semester, I took Thermal Physics to complete that minor. I've never met a physics course I didn't ace, so I figured "easy A".

I'm quite certain I was the highest scorer in the course and was a solid B+ before the final. I took the final and felt really good about how well I did. I thought sure that professor would curve (or otherwise adjust the grades) and I'd be the one that threw off the curve.

I got my grades back. I got a C. My only C ever, in fact. An A (what I expected) would have gotten me summa cum laude.

The same semester, I took a statistics class. Paid exactly zero attention in class. The class took place in a computer lab for no good reason other than I'm guessing the other classrooms were booked. I played a fast-paced Quake-like FPS every class all class. Got an A in that course.

But that fuckin' thermal physics class.

Years later, a coworker of mine who was an alum of my alma mater told me that they'd taken the professor who taught that thermal physics class off of teaching permanently due to his completely unreasonable grading practices.