At my 2nd day of a job, I deleted the entire stack of the test system with a misplaced rm -rf.
I crapped myself thinking I'd be instantly fired. My boss made some 'angry' sounds, then told me it's not the biggest issue as they needed to try a fresh install of the new version anyway (as thats' how the new version would be rolled out in production rather than upgrading, which is what they normally did on the test servers.)
This also allowed them to fully test the backups, pulling the older data from the production backups, anonymising it as required and also finding some faults with various processes that were included but didn't work after the upgrade. In all the test system was down for about 4 days instead of 1, but the fixing of the systems to allow it to get the go ahead in production took a month or more. If I'd not 'slipped up' then they wouldn't of known these issues until trying to go live in production and if so, it would of been a very long night of around 6-8 hours reinstalling the older version back into production (after the 6-8 hours of installing and testing the new version).
This attitude of 'we can't afford to test it' is utter bollocks. You fire up as many vm's as required in the cloud, and you at least verify the _data_ is there, even if the functionality isn't. It's bad to find the code for the production system isnt' backed up as much as you think it is, it's unrecoverable to find out the data is gone.
These guys got lucky, if he hadn't taken that copy 6 hours before they'd be dead in the water and the company would be gone.