> I wasn't fired and we fixed the issue very quickly, but man I felt the edge of that sword really close to my neck.

The same experience. I was working for a pornography company and where I was configuring load balancers. I had a test page of semi-naked red deviless with the words "Hello Minion" above her head which I had forgotten to remove.

So during peak times, when the misconfigured LB went active it threw that page to the public, advertisers and the other white labelled websites.