Porn buddies is a Jeffism and a symbol of how close friends two men can be.
While at work, Susan asks if Jeff knows Steve well, and Jeff says that they are porn buddies. Porn buddies are very close friends who have promised each other that in the event of the other's sudden death, the survivor ("... upset though they may be...") will rush over to the deceased's home and remove all of their pornography before parents or other loved ones can find it. The survivor, of course, will get to keep the porn he has retrieved. ("Your best friend's dead, but there's a bright side to it!").
Jeff saw an upside to the arrangement since it only stipulated that the porn be removed not destroyed. ("Flushed").