I created a 2x10 gigabit loop directly to the data center core of a regional health system on the consolidated virtualization rack that held ~80% of the applications back in 2012. It also took out the PBX. Thankfully it only took me just about 5 minutes to realize what I had done and run from the office area to the data center (in the same building thankfully) to set it back.

I thought for sure at minimum I was at least going to end up in a high pressure meeting about root cause and so on... no doctors complained, no ticket was ever created, the only mention that was ever made to me was "heh, was it you that broke things?" as the SAN guy was heading to his car and I ran past him.

Apparently 4:25 PM is a better time to break everything in a hospital system than the 2:00 AM change windows they schedule and nobody is going to bother calling support when things are working again by 4:30 and they just want to end the day. Service desk guy laughed at me when I apologized and he said he had 0 calls about it by 5:00.