An individual who appears to or does own a small dog. Specifically a ratty little thing that needs some form of coat in the winter; and by kicking standards, you could easily clear your garden hedge if it pissed you off.
Ryan: Sandy, you are such a poochie twat.
Sandy: what's a poochie twat?
Ryan: means you like like you own a small dog. Dick.
anon: I'm going to kick you in the balls you poochie twat