To whom it may concern:

If you used Facebook's search bar feature yesterday and were able to see your "top 5" friends, then there will be a PHP file containing the "o" ranking of every single one of your Facebook friends stored somewhere on your computer.

Please note: this tip applies to anyone whose computer saves temporary internet files.

(1) Open your "Temporary Internet Files" folder. (For example, from Internet Explorer, go to Tools > Internet Options > Settings > View Files.)

(2) Within the folder, look for files last accessed on May 13 around the time you first tested out the Facebook search bar function.

(3) You should be able to find a PHP file called "typeahead_search."

(4) Save this file to another folder and open it with a text editor like Notepad (or the Mac equivalent). You will see that the file contains script for every single one of your friends. (See the script here for an example.). If you search within the file for the name of any of your Facebook friends, you will find their ranking after the letter "o." The five people with the lowest "o" rankings will be the same as your "Facebook 5."

It was part of the autocomplete for the search box. The file the server sent when you clicked on the search box was a big list of Friends and groups (that it used to autocomplete when you type) like this:

{"t":"[Dude's Name]","i":2401357,"u":"http:\/\/www.facebook.com\/profile.php

?id=2401357","o":216,"it":"","n":"Northwestern"}

for me the "o:" value here is 216 for the vast majority of the names,
216 being my total number of friends, but some are lower - lo and
behold people with 0-4 are the five people that show up in the search
box

o's just a ranking thing, like so when you type "a" it uses the o
value to figure out which names should come first, then everything
that's 216 is just in alphabetical order

The only thing that remains is how they computed the o values, I
assume the method was something nefarious. Anyway it's gone now, but I
hope this helps. I'm not affiliated with facebook or anything.

• The "It's People YOU Search For" Theory
  A passionate reader writes: "jesus.... PLEASE correct that facebook post. it's the five people whom YOU SEARCH FOR most often... not the other way around. it's driving me crazy reading through all the comments seeing people getting mad at facebook for absolutely no reason."
• The "It's A Coding Error" Theory
  From a Facebook discussion thread: "I suspect it's meant to be the people whose profiles you look at the most, but that they're referring to the wrong statistics (human coding error) and it's actually the 5 who look at yours most. I think it's a mistake because Facebook wouldn't do something like that deliberately, it goes against their ethos of anonymous browsing, but it definitely refers to a statistic that they're keeping, and between the [limited] information that the coding context gives and the nature of the names (after cross-referencing with 7 of my friends), I'd say they're accidentally calling up the 5 people who browse you the most."
• The "Search Frequency" Theory
  A reader attempts to parse the Facebook algorithm: "I have a theory. I think it's matching the frequency of times that you search for someone with the frequency of times that people search for you and it's an attempt at interpreting who your best friends are."
• The "It's NOT The People You Search For" Theory
  A commenter tries the process of elimination: "eek — okay so i went on my secret stalking-only facebook page, where i have no friends, and tried it. nothing came up, which makes sense, cause it's a whack name. however, the people i use it to stalk didn't show up either, which means it cannot be tracking the people we stalk."
• The "Facebook Says You Like These People" Theory
  A commenter claims to go directly to the source: "OK, my friend emailed her friend that works for the Good Book and here was the response (emphasis mine): This is the canned response we've been using:
  The five friends that you see below the search box are populated based on people whom we think you'd be most interested in. Taking into account various factors, we attempt to make an educated guess as to who it is you're looking for when you start typing a name in the search box. Please note that this information is only visible to you and will not be shared with your friends. We hope that this feature is helpful and we appreciate your feedback. Let me know if you have further questions."

[UPDATE: Although the "down arrow" feature seems to have been disabled, you can still pull up the list of five by typing a period (".") in the search box.]

Stirr's mixer last night brought startuppers, marketers, and investors (and one gossip blogger) to Palo Alto's Fanny and Alexander bar for a handful of one-minute dot-com presentations and a night of drinking, demoing, and awkward schmoozing.

Demo-ers included:
Sean Savage of cafe-driven PlaceSite
Vinnie Lauria (who — ladies — is new in town and hot as hell) of social IM service Meetro
Andrew Martinez-Fonts (thanks for the ride, Andrew) of p2p-loan site Prosper
Adam Siegel of Inkling Markets (the wisdom of the bookies)
Scott Johnson of Ookles — I wasn't listening by this point. Sorry, Ookles.

The main event was the three-hour laid-back schmooze session. Beer was $4.50, and hard liquor could be had for three bucks. This, the 6-to-9 timing, and the lack of free food meant a roomful of drunk dot-commers.

Meanwhile, on the deck out back, a club of young VCs ("Future Partners" of something or other — young bucks freshly post- or pre-business school) held a session out back — with food! — that was quickly invaded by startups hungry for kebabs and Round A funding.

Photo: The Stirrers [Philosophy Geek on Flickr]