I think its an unwritten right for anybody in the construction field to use the porta-potty on another construction site in which site they may not be working on.
Squatter's rights?
not necessarily so.....
when we built our current house, we had the camper and a blue room on site.
The contractor started building on the tract next door- well 400 feet away- but was doing it on the cheap. he didn't rent his own outhouse but kind of implied to his folks that they could use ours.
Mrs. File was VERY unhappy about this discovery and padlocked the facility. That one poor plumber was so miserable standing there begging her for the key....:-D
[sarcasm]I always depended upon the written and documented black marker evidence left on the side of the portable unit from my last visit.[/sarcasm]