Physics in general is pretty easy for me to grasp, but one thing I lol'd at were some test questions.
In my first physics class, I got counted off when I made a math error and ended up with an odd answer. The professor was all "you should've looked at your answer and figured that it didn't make sense." Yeah, point made.
Enter second physics class. The problem was something odd and I got something bizarre, like a bird flying at 300 km/sec. I thought "this isn't right~ IMPOSSIBLE SPEED." So I did some stupid steps and thought I got to the answer -- wrong. Prof saw it and was all "why'd you change your steps" and I said "Because the answer was impossible." Prof said "THE MATH WAS RIGHT IMPOSSIBLE DOESN'T MATTER. B MINUS"
Jam it back in, in the dark.