Last weekend we went to a little schooling show, being the only ones riding 1st level we went first. At the salute, Primo promptly parked out and peed. At the end of the ride, the judge said that I better not miss X on my next test since my horse decided to mark the spot.
Sadly he wanted nothing to do with his pee-spot and wouldn't step anywhere near it. All the little kids after him thanked us for marking X.