Mostly random. Fakku is identified as an adult site (hence the use of Black Label Ads), so a lot of the ads are geared towards similar adult material because it assumed that someone who is viewing Fakku might be interested by the advertisements.
Jacob can block certain ads from appearing, but it is more hassle than it is worth, so general adult ads are what show up on this site regardless of the specific types. It doesn't have anything to do with what the individual viewing the site happens to frequent.
Similarly, this is where the bots come in (i.e. YahooBot!, GoogleBot.) At any given time there are probably a handful of bots that are viewing every facet of this site, and use that to determine what type of ads are appropriate for this site (if the site uses Yahoo or Google ads) and also effects how the site is shown on their search engines.