I'm going to be attending my mom's graduation in the San Francisco area on Thursday, and thus have to miss classes on Thursday and Friday. This is the second-to-last week of classes, and my lab final exam is scheduled for Thursday and Friday, so I was careful to line up subs many weeks ago.
On Sunday I learned that one of my subs had just gotten out of the hospital, and had to cancel. And, just now, I learned that my other sub is currently in the hospital recovering from emergency surgery.
Lesson learned: Don't sub for me.
[Update: I wasn't able to find any other subs, so ended up having to cancel classes on Thursday and Friday and delay an exam. I've rarely seen my students so elated.]