It's operating on the premise that friends of your friends are good candidates to be your friends, too. I don't really get the whole numbering thing, but it's interesting to look at a list of names rather than use LJ's "friends of friends feature" which shows recent posts (and is only available to paid members), if I recall correctly, or going to each of your friends' userinfo or friends pages and trawling for names that look promising;)

:: shrugs :: It's not like it's a big deal. That's what gets me about all the clamor at the creator's original post - people are making a huge deal out of the fact that it doesn't mean much.