Please note that the code they give you to include on your site includes a spam-ish link at the bottom. Feel free to delete that.
Update: Dan has pointed out in the comments that the site is broken and doesn't give you a score and I wouldn't suggest bothering to take the test. (Though it's not any more shady than they already were -- http://www.howmanyfiveyearoldscouldyoutakeinafight.com/ was already redirecting to http://www.justsayhi.com/bb/fight5. I'm guessing that their give-you-your-score code has crashed.) More entertaining, anyway, is to just go read the old forum thread from 2005 that started the whole thing. (It's a Poker forum, by the way, but one that seems to foster interesting side-discussions.)
(via Shaun, of course)