This came from a facebook conversation with Cynthia Sonier, who produces the strip Sooky Rottweiler (available on Tapas at https://tapas.io/series/SookyHeadsetChronicles  and https://tapas.io/series/A-Christmas-Mittaines). She had a panel which showed her reactionary silver tabby Mittaines sitting on the toilet. And I remembered that my first cat, Sunday, did that for real. Not only that, when she was outdoors she would pee while sitting over drains, just like Jones is doing in this strip.