This is one of my puppies, Luna.
She's a 15 week old pitbull mix and the most photogenic dog in the world so I have a tendency to get photos of her in awesome positions.

We call her "Lunatic" (even though her name really is just Luna) because she likes being held upsidedown, cradled like a baby, and sleeping on her back. She never runs out of energy and likes beating the hell out of her brother.

I have no idea what they're mixed with... She's very lanky and has a super long tail.