Fucking #Brightspace decided to zombie-reactivate a quiz from last semester that I didn't warn my students about because I didn't intend for them to take it.
However, they all took it (and some got really good scores). After almost 30 intro stats students took the quiz, one emailed with a "Um, professor...?" email, and that's how I found out this was happening.
I'm kind of impressed with the students. Of course, one or two of them will dredge this up at midterms or finals when they don't like their grade, and complain to my Chair or Dean about my "surprise quiz" or "disorganized LMS" or something, but for right now it's nice to see how they buckled down and learned things.
Now they're all going to be more prepared for class tomorrow than I imagined :)