After moving boxes and boxes, and more boxes, a slippery beam proved no match for my adventurous footwork. I slipped, and put my foot through the ceiling, followed by both legs and a bit more besides. Luckily, a beam interfered with my downward trajectory - almost breaking my hip in the process.
The hole suitably made safe(ish), I was able to stand back and reflect... Now, I feel sorry for anyone who hasn't experienced the freefall joy of putting their foot etc through their ceiling (or, if they can pull it off, someone else's ceiling). It's a kind of domestic bunjee-jump, completely unexpected, and over before you can do anything about it. Also highly dangerous, of course, as I'll be advising when telling that story for years to come...