So sorry to snicker!!
This happened to a lady, Martha, that worked for me. She took her dog to the dog park and was chatting with a man sitting on the ground. As she was talking to him, her dog (big dog - can aim high) walked over and peed all over the guy's back!!

Luckily the guy was a big enough dog lover that he didn't freak out and was quite kind about the whole thing. Guess her boy was letting that guy know that he owned Martha, the park, AND the guy.