When the computer you are working on is not the computer you are working on
Post OS upgrade, I finished off some bits and pieces using the vt220 compatible sat on the minicomputer and turned the reset key. While the key was in the "full reset, yeah you asked for it lol" position I noticed the label on the computer didn't match the name of the system I was working on. And remembered the point I raised myself a few days previously that the new policy of putting consoles on any available surface was a bad idea in itself, but an especially bad idea when "any available surface" included typically unrelated minicomputers whose top was a convenient desk height.
So yeah, having raised this point myself, and having a head full of filesystems, software versions, if the various patches and updates had been invited along to frolic and so on I'd subsequently forgotten that minor point. The computer, the computer. Oh yeah, that thing the console is sat on. Computer! Reset key! Final stage of this tedious experience which my coffee-deprived mid-afternoon crash just thought "thank all the expletives in the universe that is over". And then the realisation. The computer; well it's a computer, but not The Computer. Not the one I am working on. If it is The Compuer, it's... oh bugger, the one that the "Death Row" executive offices use. The executives themselves didn't partake, I mean this was the early '90s and keyboards were women's work, but their PAs were quite fearsome. So, er, sorry about that, couple of dozen high-power and probably now quite grumpy senior people whose work I've just nuked.
The fallout was surprisingly mild. I was sheepish about it and my admission may have got about as far as a rather high-pitched <eep>, the Most Senior Of All PAs seeming actually quite relaxed and "well the computers normally work all the time, these things happen" and while I'll never be entirely sure if she knew "these things" were due to the sleep-deprived figure in front of her having a bad day and inadvertently blundering about and causing chaos... oh, who am I kidding, she knew and was gracious enough to let me go on my way without further ado. No complaints were filed, or my manager did a very good job of composting them. The wayward console problem was solved soon afterwards using a curious little RS232-based LAN controlled by a COBOL application on a 286 PC. Sounds a bit ancient but worked really well.
I didn't reset or otherwise crash any more machines but I did have various other escapades and misadventures, largely because I was in my early 20s.