This just happend last Thursday. I was sitting through this boring lecture and next I felt someone tapping my shoulder (I dosed off). I opened my eyes to see EVERYONE staring and laughing at me, then my prof gave me a lecture for falling asleep and not taking notes. I was kind of embarrassed and whenever I get embarrassed I have giggling fits, so we all were laughing for like the next 10 minutes. It was a cycle that day because I dosed of several other times. My prof was pissed.