While lecturing today, one of my students knocked an entire pile of books onto the floor. It was a distraction, but I didn't think much of it. Then another student did the same thing about ten minutes later.
When it happened the second time I stopped lecturing and said, "Am I really that boring today? Everybody seems to be falling asleep and knocking things over."
The first student approached me after class and said, "It's not that you're boring, it's just that I'm narcoleptic and they've just changed my medication again."
Fabulous. Another instance in which I've unwittingly mocked someone for a condition they have no control over.