Stanley sometimes loves digging holes in the dirt at dog parks. We live in an apartment so we don't have a backyard so I'm not sure if he'd dig at home. I've never seen him digging in the area around our apartments though. It's only at the dog parks. I'd like to discourage this behavior b/c he gets so dirty and we have to fill in the holes. Plus, he usually starts a trend and then other dogs at the park start digging alongside him, much to the chagrin of the other owners there. We usually say "uh-uh, no dig" in a stern voice but he's just so stubborn. He'll keep digging until we physical pull him away and then he'll run circles around us and eventually end up back at his digging space. What's the best way to discourage this or redirect him?