When I worked for a company who worked with big banks / financial institutions we used to run disaster recovery tests. Effectively a simulated outage where the company would try to run off their backup sites. They ran everything from those sites, it was impressive.

Once in a while we'd have a real outage that matched the test we ran as recently as the weekend before.

I was helping a bank switch over to the DR site(s) one day during such a real outage and I left my mic open when someone asked me what the commotion was on the upper floors of our HQ. I said "super happy fun surprise disaster recovery test for company X".

VP of BIG bank was on the line monitoring and laughed "I'm using that one on the executive call in 15, thanks!" Supposedly it got picked up at the bank internally after the VP made the joke and was an unofficial code for such an outage for a long time.