Another porta-potty was found torched in San Francisco this past Sunday afternoon, but this it happened in the Potrero Hill neighborhood. Reported at 4:25 p.m., the flame-up happened at the intersection of Kansas and 15th streets. Could this be a copycat? We can't imagine the Toilet Torcher, whose neighborhood preference of immolation are swank Russian Hill and Nob Hill, would dare stray from the upper echelons. Anyway, this most recent outhouse arson is the 23rd incident since early November.