When I Accidentally Wiped My Co-Worker's Drive

I was just trying to free up some space on my hard drive by deleting a bunch of old files. Unfortunately, I mistook my colleague Alex's external drive for mine and wiped it clean before I realized what had happened. It was an epic case of 'oops' mixed with 'uh oh.' So here’s my question: Have you ever messed up something this badly at work? Let’s hear about your worst IT blunders!