Really? I thought pigs were 2-cycle animals (eat their own output on the first iteration, like rabbits), no? I mean, sure, some minority of dogs eat their excrement -- the same dogs that end up in the homes of Blue Collar Comedy comedians. Tough contest I guess. I had a dog that rolled in every rotten dead fish it encountered by the lake. Not sure why.. maybe it serves as a good cologne to attract the females.

(edit) dogs might have a better memory than cops.