You Are An Idiot
This is just a simple joke, which makes a lot of small moving windows on your screen. It originally appeared at http://youareanidiot.org, but it was removed later. You can still see the original version on Web Archive: https://web.archive.org/web/20040804124508/http://www.youareanidiot.org/. To try it, you need to enable Flash player and disable Pop-up Blocker.
Recently it was recreated on https://youareanidiot.cc/, you can watch the whole story of this website in this video.
I recreated this 'virus' as a Windows desktop app, which has the advantage of that you don't need to enable any pop-up blocker, it works just out-of-the-box.
By default, it opens new windows under the same program instance, so you can easily close it with Task manager. To make it a bit more annoying, you can run it from command line with --dangerous flag. That makes new windows open as new program, which completely bloats both your screen and Task manager and makes it effectively unclosable.
The principle is simple: when you try to close any of the windows (either clicking on the close button or pressing Alt+F4), it spawns a number of new windows. Soon it starts overloading your computer, which may then crash or freeze. It really doesn't do anything dangerous or harmful, it never touches any of your files, so you don't have to worry.
You can find the program's full source code on my GitHub if you are curious how it works. The source is in a single file (Idiot.cpp) and contains a lot of comments to describe what is going on.
Warning: Before launching this app, you should first know how to terminate it (through Task Manager).
Disclaimer: You use this software on your own responsibility
Download (OLD VERSION, I WILL RELEASE A NEW ONE SOON) (Idiot.exe, 1.05MB)