I was in college during the years leading up to y2k and supported myself at the time getting IT infrastructure ready. Some friends and I decided to write a "virus" that, on bootup, checks to see if the current date is in the first week of January 2000 and if it is and a backup of the fonts is not found (so it'll only run once) then it'll back up your fonts and alter the originals to replace the y character with the k. This affected everything system wide.

That created more chaos than anticipated.

Every time you log in, maximize a window, lock your PC, etc, your desktop icons randomly arrange themselves by penis. Open a folder, forced to display files as icons and arranged by penis. Try to view all your open windows on your desktop, you guessed it, penis.

In a programming class, one of my professors sometimes remolety opened the xeyes program (Linux program that opens a pair of eyes that follow your cursor) on students that were not paying a lot of attention.

I had a friend who sent me a "Y2K fix" program back in '99. Said it would patch the error so I'd be safe. When I ran it, it swapped the letters Y and K on my keyboard.

I Rick Rolled my entire school this way. Write a program that maxed the volume and held it there at 100%, minimised all open windows, downloaded a photo of Rick Astley and set it as your wallpaper, then started playing Never Gonna Give You Up. The only way to stop it was to power off the computer or wait the song out, then manually fix your wallpaper.

I saved the executable in a publically accessible location on the school's server that I shouldn't have had write access to, and sent a cleverly disguised link to a mate. He thought it was hilarious, and forwarded the email to a dozen of his mates. They forwarded it to all their mates, and pretty soon no teacher could go 60 seconds without another one of their students' laptops interrupting the class at max volume.

Best bit? I "taught a valuable lesson in cybersecurity" and didn't get in (much) trouble!!

I had a boss that wasn't exactly technical. I wrote a power shell program that would randomly every 5-30 minutes give a pop-up that said "good job", which he always said regardless of what was going on. Placed it in his startup folder on his machine. I thought he would figure it out and tell me to knock it off.... Well I forgot about it, 9 months later during my annual performance review it popped up while I was looking at his screen. He apologized and just alt tabbed it away.

I offered to take a look and see if I couldn't stop it, and he said yes and then walked away to take a break. I then deleted the script I put on there. He gave me extra performance points (meaning a higher pay raise.)

Three options come to mind.

A virus that adjusts your mouse sensitivity by like 5% every time you unlock your computer. Just enough that existing muscle memory is off, so you either have to adjust to the change or change it back every time.

A virus that installs and/or sets a similar but not quite right keyboard layout, and swaps to it randomly few boots. For example, setting the keyboard to Canadian Multilingual Standard instead of US English, where its only some of the punctuation keys that are changed.

A virus that randomly pops up a terminal window and outputs suspicious-looking text, and closes itself before the user has time to read it.

I used to make a batch file that opened a command prompt that opened the batch file again and again and put it on the computers as the internet Explorer logo.

People would get so mad when they opened it as a cascade of cmd would open until the computer crashed

So something like that i think

Autohotkey script that shuts the system down whenever someone types out certain key words. They of course include words related to looking up the issue like "help", "randomly", "virus" and so on. Not the most sophisticated but one I've actually done before.

Edit: Forgot to mention that ahk needs to be installed and the script must be placed in the autostart folder. Both can be achieved on a coworker's or family member's machine with a ducky usb stick.

I wrote a simple script once that ran in the background and all it did was toggle the state of the caps lock key every 30 minutes. I set it up on a co-worker's computer as a scheduled task for an April Fools prank one year. I thought for sure he'd figure it out pretty quickly, but by mid-day, he had completely disassembled his keyboard, convinced the button was getting stuck due to gunk buildup. Eventually I ended up just disabling the task so he thought he had managed to fix it himself.

Simple, every now and again switch a key input with a neighboring key. Imagine slowly losing your confidence in your motor skills as you just can't seem to type properly no matter how careful you are.

It would do it like once every 10-1000 minutes, you will never catch it and slowly lose your grip on reality.

Oh, I have a seemingly harmless idea so evil, it will ruin the internet forever.
I will make it so every time you open any website, there will be a popup with a question that asks you to invade your privacy, and you can allow it to do so with one click, but you will have to dig through menus if you want to avoid it. Then, after some seconds, another popup will appear, asking you to create a login, no matter what you do. Then, it randomly will ask you to share your location. Yes, with a popup again. Then, just as you thought you're done, another window will open, grabbing your focus, which will demand you talk to a chatbot, and you can't close this one, only slightly minimize it.

Supposedly there was a DOS virus that would spawn a pacman that would eat your letters as you typed them.

The version I recall was once if those Flash animations with a cute squirrel or whatever saying something... but it was really quiet so you'd need to turn up the volume to hear. Then partway through it changed to sex stuff and blasted out in a voice like a monster truck announcer

"anal sex dot com, all anal, all the time!"

Uhh, it was "Hey everybody, I'm looking at gay porno!" and then it proceeded to spawn hundreds of internet exploder windows pointing at goatse.cx. Thank God I was at home, alone, when it got me.

In the early 90s there was a virus going around that made the floppy drive's loading noises play the Imperial March.

A screamer virus could bring the world to its knees.

How about a programm which screams "aaaaaaa" after you unlock your screen. Barely hearable at first and it gets louder with every minute. People who don't know how to remove it would have to lock and unlock their screens every 5 minutes or so.

There was a guy in my dorm who really didn't like his roommate. Really, really didn't like him. This was in the early aughts.

So one day he goes on his roommate's computer and puts a text file in his startup folder. The file says, "Your computer has been infected by the Snood virus!"

For context, Snood was a free video game people downloaded in the early aughts. Basically the same as Bust-A-Move, which probably doesn't clarify anything if you didn't already know what Snood is.

Anyway: "Your computer has been infected by the Snood virus! If you don't score [extremely difficult but not completely unrealistic high score] points, all of your files will be deleted!"

He laughed to himself and promptly forgot about it.

Weeks later, the roommate is on his computer in the middle of the night.

"What are you doing up? Go to bed."

"I can't. It's this stupid Snood virus."

I remember a harmless over that just randomly opened your CD tray while it ran. Called something like cup holder, or something like that.

Shit that was a long time ago...

Finds anything and everything that can be set to dark mode and sets it back to light mode, but not while you're using it and not immediately.

Change the start menu search so instead of finding local applications and files, it searches the internet.
Would be even funnier if it used the worst search engine available.
Oh wait...

On my dads computer, back in the day, I set the sound for every action in Windows to a silly song i downloaded off kazaa (Windows xp days, i believe)

So this was the sound that played for clicking the start menu, hovering over programs/apps, whatever it was and making that menu appear, and any sub menu for individual games or apps following that. Any kind of prompt like errors or "are you sures" etc, minimising/maximising a window. Everything!

That's what my virus would do. I just need the perfect sound to apply. Maybe that annoying tiktok song "Oh no! Oh no! Oh no no no no no!"

I have made some silly programs. One that moved the mouse pointer one pixel left, then down, right and up. It was quite annoying. Another that moved the mouse pointer when you reached the edge of the screen, touching the rightmost pixel row would move it to the left side of the screen and vice versa, same thing with top and bottom.

used to be fun at the office to take a screenshot of someone desktop, and make it the desktop background, then put all their icons into one folder.

When I was in high school I made a .bat file that autoran when you put it in a device. All it would do is open the disc drive every 90 seconds however it did convince one teacher that she had a virus which caused giggles all around.

back when I was in school someone wrote a script that just openened the optical drive at random intervals and put it in the Autostart of every PC in the Comouter room

It was not a virus, but still great fun: coworker had a fat UNIX workstation, but no idea of the particulars except for the program he was using. I knew my ways around such machines, and I could log in from another machine via serial terminal.

What the coworker knew about the audio capabilities of his machine was the occasional "beep" it made. I found the "auplay" command, and a list of 8-bit audio samples.

So one day I was sitting at the PC next to him, logged in, and command ready to run, and waited for an error message to pop up. Then I pressed return, starting "auplay laughter.au".

That face.

Occasional mouse and keyboard lag up to 1 second.

Sounds like a variation of the Ohio virus. I used to have a copy of it for the Amiga Amstrad. It would trigger and make the piezo speaker say “Ohio Ohio Ohhhh!”

In my highschool programming class we made a TSR (in Borland pascal) that would change every 15th keypress to an "e". It wasn't self propagating, so it wasn't a virus per day, but it was highly annoying. It survived on memory after the netware logoff, and you could only get rid of it by rebooting.

We also had these everex brand 286 or 386 computers.... They had a little LCD screen that would read out what sector/track was being read on the disk. We found the memory address (80h) where we could write arbitrary text to the LCD. That was fun.