Story time! This happened several years ago, back when I didn't have a computer and I was just using the computers at the university. They had 8 iMacs all in a row, and I would sign into one and do my work.

Now these computers have Deep Freeze on them, which is a fancy hard disk driver that treats the entire drive as copy-on-write, so when anything writes to the drive it makes a copy of the block and writes to that instead. That way all your changes are gone when you reboot. It's a real nifty idea, but it's annoying that you have to reset all your settings the way you like them.

So as part of my setup routine I signed into iCloud. This automatically synced my browser history and my email, and various other things I didn't really care about.

One of those things I didn't care about was Find My Mac. I found this out next time I signed into iCloud and saw the university computer on the list. I had never seen these computers on the list before since normally the computer reboots and forgets everything when you log out. What I think happened is the sysadmin forgot to check the "reboot on logout" option in Deep Freeze. So I was like "I wonder what would happen if I passcode locked the computer?" I clicked the passcode lock option and entered 5555, and it seemed to work.

The next day I come in and the particular computer I locked was gone. I thought "oh God what have I done". So I inquired with the sysadmin (who I really hope is not reading this) and he said "oh, someone got into the Find my Mac thing and locked it down. We were trying different codes, since if we couldn't unlock it we'd have to send it to Apple and provide proof of purchase and that could take weeks. We had tried all the obvious ones like 1234 and that wasn't working so I was about to give up, but then I tried 5555 and it rebooted! So yeah, it'll be back soon, and I decided to try installing OS X 10.11 on it because we'll all need to upgrade sooner or later eventually and it's best to have tested a bit first."

So in the end I somehow made it out with my skin still on, and also with El Capitan on one of the computers, which was the only one I used after that. Not so bad! Oh and if you've manged to read all the way through you deserve a cookie 🍪😄