"10 Things Every College Professor Hates"
Pretty much nailed it. #2 is probably the most apt:
Don’t ask the professor if you “missed anything important” during an absence.
No, you didn’t miss anything important. We spent the whole hour watching cats play the theremin on YouTube!
Of course you missed something important! We’re college professors! Thinking everything we do is important is an occupational hazard. Here’s an alternative way to phrase it: “I’m so sorry I missed class. I’m sure it was awesome.”