A simple website designed to open thousands of HTML tabs on your browser.
CrashUrPC opens many about:blank windows on a browser along with opening MORE CrashUrPC windows that do the same thing. It's designed to crash your PC.
Also, note that this is patched on most modern browsers, as browsers nowadays prevent popups. But if you manage to steal your friend's computer for a while, this still works fine.
If you think you can make this project better, feel free to fork and make a pull request. :)