Fortunately not as serious as other comments. For context, I have autism, and I frequently stim by making random noises.

One day I was at a global online meeting with very important people. I thought I was muted, so I said “MEOW”.

Suddenly everybody goes quiet and somebody says “did anybody say ‘meow’?”

I quickly turned off my microphone, and fortunately nobody mentioned that again.

I worked for the railways, in commuter trains. My job was to harass innocent passengers by walking back and forth and enabling them to buy a ticket should they need one. And at certain routes also check the tickets of every new passenger.

It was nice using a dialect from eastern Finland, the Savo dialect for that. It has a tendency to change plain vowels for diphtongs. It adds a kind of a “wee-wow” twang to the language. For example the word for “closet” is “kaappi” in standard Finnish, “kuappi” in the dialect spoken in Savo. The “aa” is just a long “a”, sound. Pretty much the same as the “a” in the English word “car”. And “ua” is pretty much like “oi” in “choir”. Imagine pronouncing the word “car” with the “a” replaced with the “oi” sound of “choir” and you might get an idea of how that crazy dialect likes to mangle every damn word. And the “ar” in “garlic” would be pronounced with the same change as well. Etc.

And maybe at this point it’s worth mentioning that I still had a fully male gender expression at that point.

So, we have just left the station of Haarajoki. In the Savo dialect that would be “Huaarajokj”.
I enter the part of the wagon through its end door. I start shouting “Haarajoki passengers, tickets please!”, but. But.

As it happens, “huaara” is how they would pronounce also the word “huora” over in Savo. And that happens to mean “whore”. Luckily I noticed. So, I managed to stop myself from uttering anything further. Unfortunately, I only managed to stop after having already said the first half of that word, “huaarajokj”: Yes, “huaara”.

In other words, I entered the passenger wagon through the end door in the railway worker’s uniform, immediately bellowing “WHORE!”, and then shutting up.

Definitely an “oh shit” moment!

After that:
Me: “Hm. This station is not terribly compatible with the Savo dialect, apparently.”
A female passenger: “You should have continued to the end, would have gone much less badly”.
Me: “Yup!”

Spot welded a screwdriver to the metal sidewall when I slipped trying to discharge a capacitor. At least I thought to wear gloves.

Not anything destructive (to the Company) per se, but seeing a meeting with a senior and a member of HR suddenly pop up on my calendar after weeks of waiting in limbo to be placed on a new project was definitely an OH SHIT moment.

Yep, I was made redundant 🙃

Not mine, but another’s. She stating in her Foghorn Leghorn voice “I want to say “I can’t hear you over your hair. It’s too bright!!” to her”. As I round the corner in my short Spiked Blazing Orange hair. How embarrassing for someone.

I was asked to provide technical on-site support at an event, because I knew the underlying server system under the software that project management had found to run this customer event.

They had also hired a bunch of laptops with wifi and a router for this, which was rather expensive back then (you could have bought a small car for that rent fee alone!), so a lot was hanging on this to be a success.

Of course, I knew about nothing what this job was about until I sat in the car with the project manager on our way to the first event. My reaction was: But that software cannot do what you just told me! Oh shit, indeed.

When we arrived in the evening before the first event, the server, wifi, and one of the laptops was set up before anything else, and I went to work writing a rudimetary software from scratch that would do what the customer wanted, and finally hit the bed around sunrise.

The event was a big success in all venues on the trip. The customer was extremely happy with the acceptence of the setup by the audience and the results they got.

Tooks out search on Wikipedia. I exposed a path that can perform an unconstrained Powerset Construction concurrently on 7 servers. It filled up memory and died. User retried. While cluster OOMing.

I put the localization files in the wrong folder. Thankfully, we hadn’t pushed anything to prod yet, but we were trying to figure out why everything kept crashing even though our checking tool was giving the all-clear.

It was checking everything except the localization folders.

Accidental reply-to-all set on mailman list, of 8,000 users.

Only minor at about 16 minutes and 11 replies shared.

Still had a little bit of cold-sweats, and dolly-zoomed my surroundings.

I was working as a short order cook back in the 80s. One night after closing we were having a few beers as a farewell to a co-worker. We wanted some music so we taped our walkman earbuds to the intercom microphone. Came in the next day, our busiest day of the week and found out we had blown the amplifier.

At an online gaming company back in the late 90s, I deleted a file folder whose name was my first name. I had been there about a month and figured I must have created that folder for some dumb reason while I was ramping up. Turned out it was created by a previous software dev who happened to have the same first name as me, and it contained the production software. Essentially I blew away a good part of the external website.

Fortunately somebody found another copy and restored everything, named it something sane and put it in a sane place with access control.

Admittedly it was sloppy of me to delete a folder without at least looking inside it, but I really didn’t feel too bad about it because standards at this place were so low - they had no concept of source control, dev/test/prod environments, or much else. Everything they did was cowboy.

Reading through the comments, I remembered my first day on my second ever job, where we were instructed to turn off computers and power strips too, at the end of the day. When I turned mine off at the end of the day, I found out other power strips were using mine, so I turned off other people’s machines. Unfortunately, the guy that gave us the instructions was first to leave in the evening and hadn’t have his machine turned off that way.

Also remembered that I once broke production server (maybe it didn’t get to production, can’t remember) by adding a single line of log, I didn’t notice that what I was logging was computationally intense, so it halted everything eventually, but it was barely reviewed because it’s just one log line

I’ll tell you my biggest destructive moment was getting a single phase 440v/50hz motor from Europe for some equipment (I’m in the states) and it had the worst nameplate I’ve ever seen on the motor of whether to remove the capacitor across the two phases or not. Turns out the cap got left in only on 220v. We put 480v/60hz on it, which is within 10% so it’s fine but the cap should have gotten removed. Stupidly I only hooked up to like a 30A twist-lock connection off the wall for testing before it got installed rather than the 6A it needed in the panel. The cap burned itself out, started a small fire, caught all this soundproofing insulation crap on fire. Couldn’t get another motor for months. Big whoops

Decade or so ago, logging into a work computer and suddenly the screen is just tiled with the word “virus”, but a bit janky looking like it was a screenshot of the word that was enlarged and tiled with no thought to whether the right side of the image lined up with the left and such - it was a very 90s cheesy movie like depiction of what happens to your comp when you get a virus, like you’d expect the next scene to be some shady hacker on the other end exclaiming “I’m in!”

Then again, I don’t know jack fuck about viruses, and the machine is behaving super weird, so I unplugged the internet cable from the back, and called my manager over. He had a similar “…is this for fuckin real?” reaction that I did. Mind you, this is a hospital, so if one of our computers is fucked, this is a big deal for potentially leaking patient info, so even though it had that kind of slapstick appearance, no one was fucking around with it: so, manager pushed it up the chain, and after a few mins a fucking SWAT team of IT guys comes in and starts doing their own assessment.

After some deliberation, they start troubleshooting - keystrokes and whatnot don’t seem to be responsive. One of them eventually reaches back behind the monitor and ‘poof’ the screen pops back to the normal login screen.

So, that facility had a fancy custom login screen, which was some generic desktop background type scenery and a wall of text that none of us ever put any thought into. One of the snipits on that wall of text was instructions on what to do if you suspect your machine has virus (which was basically what I did - leave it running, unplug it from the internet, and call IT… hooray, I’m not completely stupid!). What ended up being the cause of the “virus” tiling was the fucking VGA cable slowing worming its way out of the back of the monitor - when I got to it, that thing was hanging on by a thread, and touching the desk it was on was just enough of a bump to make it cross that line between having enough of a connection to do its job vs not. That micrometer of pull of on that cable wasn’t enough to completely cut its signal, but it wasn’t enough to produce a normal display either: it just picked a random spot on the screen, and filled the monitor with that repeating image. The spot it just happened to do this to was the word “virus” in the custom login text explaining what to do if you think you have a virus, lol.

TLDR, got my management chain from my dept to the top dogs running the hospital, and the entire fucking IT department to swarm to my unit over a potential data breach that ended up being a wiggly VGA cable.

Whoops.

Mid '90s, was doing something on the company’s NT 4.0 PDC. The thing about NT 4.0, when the screen locked it would show the “Press Ctrl-Alt-Del to log in” screen, but if you hit a key or moved the mouse quick enough it wouldn’t actually lock and wake up again. So, as I’m sitting there waiting for the server to do something the login screen shows up. I’m in the zone, so I lightning quick give it the three-finger salute, type in the password (usa1, security wasn’t super-high) and hit enter. Another thing about NT 4.0, if you hit Ctrl-Alt-Del when the machine was not locked you’d get a box similar to XP’s, with options to lock the computer, log off, shut down, etc. Now, you’ll notice one of the options, shut down, starts with the letter “S”. And the key to press to select that option is also “S”. And you’ll further notice that the password I typed in also has an “S”. But all is good, it asks you to confirm before it actually shuts down, right? Except the shortcut to accept that option is Enter, which I hit after entering the password. So yeah, I shut down the company’s PDC. Fortunately it was late in the day and most people had already left so the impact was minor. But I was doing some pants crapping for about five minutes while the machine came back up.