Random crappy doodles.

He has no reason to stand up straight, unless it's to see over something or look at something far off. I guess think of a meerkat? He can stand up straighter actually, but that is reeeally uncomfortable and can only do it for a few seconds. Maybe if he needs to pop his back he will stretch out. He usually slouches and waddles on his back legs like a alligator or crocodile walks when they want to get their belly off of the ground. He's most comfortable on all fours though and walks on his knuckles like a gorilla does.