When we were looking for a dog, we went to a local rescue group. They had us take the dog on a walk in the local park, where the dog proceeded to take a drink from the lake...a very large drink. Five minutes down the trail, he stops, quickly dug a large hole, threw up, and covered it, then continued to trot along.
He must have had an advanced degree, because no one in my undergrad class ever had the sense to dig a hole first.
Needless to say, we adopted him. I think he was on his best behavior that day, because he's not that tidy anymore.