Here's something a little weird and potentially hilariously fun -- there's a little eight-character code that causes pretty much any app on a Mac to crash, instantly. Writing said code, which we had to put in an image using a Windows machine, will cause your app to crash, losing anything open.
Interestingly, it doesn't seem to work on an old BlackBook we've got running 10.7.1 in the office, so it's perhaps limited to just Mountain Lion, where we've confirmed it works in several apps just, err, fine.
Anyway, if you want to totally prank someone today, you know what to do. Just know they'll hate you forever for losing them their work. Best to do it when they've only just started, then? [Open Radar via 9to5Mac]