Sure,
In your original link, you had the url "#". When you click the link, the browser tries to find a bookmark on the current page with a name that matches the text after the #. Since there is no text after the #, the browser will either ignore it or move to the top of the page.
When you add window.open() to your link, you are adding additional functionality to the link. In other words, the link still tries to find the bookmark. So when you use Shift+Click, the browser does what it would normally do (open the window and try to find the bookmark) plus it executes the window.open().
So in you're link, you use window.open to open a new window, then you add "return false" to the onclick event to tell the browser to prevent what would normally happen on a click event.
You can add "return false" to any event that allows it to prevent the default behavior from occurring.
Adam
while(ignorance){perpetuate(violence,fear,hatred);life=life-1};