Ask HN: How to check where are your Facebook friends from.

I have now clue how they are doing that:

http://www.sterntv-experimente.de/FacebookLikeCheck/

But tests with some very small fanpages i own, are producing very accurate and amazingly fast results. There is no API for such results. How are they doing that?

doesnt work with usernames only with pages like cocacolazero