I installed a prank program on my roommates computer in college 20 years ago. It randomly rearranged desktop icons, made the mouse work like the ball was dirty, and some other stuff. He never noticed. I still have trouble comprehending that, as I notice when a single icon in my dock/taskbar is out of place.

This program seems much more in your face about what it's doing.

I believe there was some prank app's source code shared in HN before. I went to the repo to read the code and would like give them a try in my work computer. Pranks were using WinAPI and they got blocked by the antivirus. The computer is also blocked to connect to the work networks. I had to write an email to IT support that I downloaded some shit jokes to the computer and it got blocked :D