This is a dog that has been pushed too far, and has nothing left to lose.
A Pomeranian pup in China named Jin Dan was apparently so upset about getting a shave that he protested by standing on his hind legs for nearly two days, according to Rocket News 24. We assume he had that terrifyingly adorable expression of malice the entire time.
Jin Dan eventually came down on all fours, apparently resigned to his fate. As Rocket News and Gawker both pointed out, it's entirely possible that the story is made up, and the owner simply trained the dog to stand on its hind legs. Even so, there's no denying that this is the cutest/creepiest pooch ever.