This means that if you middle click anywhere in the window that isn't a link, it instantly redirects you to the "I'm feeling lucky" result for the contents of the last text selection you made. I cannot think of a single creepier usability clusterfuck.

Added fun: until a few years ago, http://www.microsoft.com was the first google search result for "http". This meant that malformed links (missing the colon, for instance) almost always pointed directly to Microsoft, on all platforms. It's a bit less baffling than it used to be, as not the wikipedia article on HTTP is the first result.