If you happen to click the link at the bottom of the page "HOME PAGE OF applet-magic" like I did, you get one of the fake virus web sites. Just do Ctrl-Alt-Del (on Windows), select Task Manager, sort on Name if you have to, right click on Google Chrome (or whatever your web browser is), and choose End Task. Or just cold start your computer.
But hey lets keep web sites with links like that off Hacker News, what do you say?