You can actually kill the "Juice Dog", as I call it, by maxing your stats out and whacking it with the Draginslayer a few times. However, it just vanishes in a puff of orange smoke, leaving no juice left behind. There's no benefit to killing it, since it only hurts you if you walk into it. A lesson in self-restraint, perhaps?
Also, there's a thing in the Abandoned House called "Your Future Self". It resembles the player almost exactly, albeit without any cosmetic items. You can drink it, but it takes a while. Is it just a morbid in-joke, or does it mean something, kinda like how Nightwatch (an obscure Marvel hero) obtained his abilities by coming into contact with his future self?