Was unscrewing old lightbulbs - the first three (yes, I'm in Procrastinators Anonymous) went uneventfully, and was standing on my bed unscrewing the third (I got a low ceiling), and in due tradition as a violist, forgot that the current was still running. Oops. But I've done that before, also without incident - this particular bulb was from the previous tenant of my apartment, and was really small, and apparently very fragile. So... a bright flash of light, a really loud POP, and there you go, the lightbulb explodes in my hand. Thankfully there was the bed to fall on, and I was a little "huh?"-ed before realising that I was bleeding and perhaps it would be a good idea try not to step on any of the glass on the way out.
Thankfully though, the cuts were quite minor, and overall, as interesting as actually getting electrocuted (done that twice, but that's another story).
How many violists does it take to change a lightbulb? Not as many as it takes to blow one up.