The Dog Breed That Has A Blue Tongue
You know how the best part of some video games are those first ten minutes, where you drag all of the sliders on the character creator to one side, or the other, and see what kind of genetic monstrosity you can make? Human beings have been doing that with dog breeds for millennia. Somewhere along the way, people had thoughts like, "What would that thing look like without a nose?" or, "What if we basically made a bratwurst that's capable of love?" and boom, a few hundred generations later, it resulted in French bulldogs, and those aggressive little dachshunds.
Still, there's at least one aspect of canine physical weirdness that might not be humanity's fault: Chow Chows, not unlike six-year-olds who figure out where their favorite sugary lunch box foods are hidden, have blue tongues. Peculiar? Certainly, and for a number of reasons. High up on that list is the fact that humans don't actually know how they got them.
Blue's clues
The American Kennel Club looked into the matter, and when they interviewed Linda Love Banghart — an officer in the Chow Chow Club, Inc. — she stated that, in spite of the breed's 2000-plus year history, there is "no documentation of why Chow Chows have a blue-black tongue." The only other official dog breed with a blue tongue is the Chinese Shar-Pei, so it's likely that both breeds share a common ancestor.
As for real answers? Scientific theories? No, not really. One less-than-scientific hypothesis detailed by Hanniko states that a long time ago, a temple guard dog carried some charred firewood back home in his mouth, and that the charcoal permanently dyed the dog's mouth its dark color. Another posits that the dogs disliked the nighttime so much that they tried to lick it out of the sky.
Stories aside, this odd physical quirk remains a staple of the Chow Chow breed. In order to conform to kennel club standards, a chow is required to have a uniform, dark tongue. Other animal members of the indigo licks club include giraffes, some cows, and polar bears. Flying in the face of logic, Smurfs do not belong to this fraternity.