It's not pee, but horse dung; they sort of micturated on the Dude's rug
http://www.rajuabju.com/literature/barnburning.htm
and contrary to the forum heading, this is not modern culture, its quite old, but I did not know where else to post my disgust at Abner Sartoris, and (horse)shitting on the Big Major de Spain's rug.