It is a general rule that the first occupant shall be the victor and a newly arriving poo-er must concede the entire restroom and come back later. However, there are times when a new poo-er cannot postpone or doesn't have the couth to wait...thereby commencing a Poo Battle.
Corporate Office Worker #2: "Damn, that is beyond rude! We should post a sign in the stall about the rules for pooing!" I'm fixin' to go poo soon. I WISH somebody would battle me! <office workers high-five each other>