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…

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 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.)

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.

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.

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…

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.”

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.

I shall write a virus that makes the computer play the “USB device detached” sound followed shortly by the “USB device attached” sound. Dee doo. Doo dee. Just that. three or four times a week.

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!”

Alt+Tab goes to a random window instead of being in the order of recency

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.

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

At first it all seems normal, every now and then a random sound effect is replaced by ominous hooting. Every hour, on the hour, a green owl flashes on the screen for a frame or two, it’s eyes boring into you before vanishing. Once every 50 or so times it pumps your volume up, selects speakers as output and let’s loose a screeching hoot. Random popups slowly ramping up “Restart your streak today”, “Where did you go?”, “Duo misses you”. At first just once or twice a day, but steadily increasing in intensity till it’s one every 23 seconds.

On somethingawful back in the day if you were on any one page on their forums for more then about 20 minutes, a audio clip would play that said something like “HEY EVERYBODY I’M LOOKING AT GAY PORNO”