noun. A particularly asshatted, navel-gazing, self-soul-sucking quality.
Real citation: "You must really try to fight against the tendency to vanish up your own arse, mate. I can live with your departure from AW/MW, but not if that's where you seem to have gone. You do have, shall we say, an affinity in that direction, like ET, say, or the little baby mouse out of Tom and Jerry. I'm only saying. I suppose upownarsitivity is the attraction of blogging. I don't get it, obviously."
(Hope, March 1, 2005, in comments at http://gollyg.blogspot.com/2005/02/at-lennox-head.html)
Made-up citation: "Even a world-renowned proctologist with a weapons-grade pair of tongs can't cure an acute case of upownarsitivity."