It obviously isn't perfect but it must have a pretty good programme to get so many right. It can usually get them right with 20 questions if you answer properly and it's not a really obscure thing you're thinking of.

The best one I saw was a chatbot program featured on the website for the movie AI. It wasn't just responding to specific words, not sure how it did it (never learnt much on AI) but it was good.

http://aimovie.warnerbros.com/html/flash.html

It's still online, try it.