Even smart surfers like us might accidentally click a disguised goatse link on Slashdot or Digg, so this style removes the goatse image. Although if you really want to be careful, you should put this site in your HOSTS file, or use Adblock Plus.
More info at http://en.wikipedia.org/wiki/Goatse
Also http://digg.com/tech_news/USA_outlaws_Goatse_links_Internet_free_speech_threatened