A Shih Tzu which has turned to the Dark Side of the Force. Since they are highly intelligent, mischevious and arrogant anyway, this is but a small step. Many Shih Tzu look like small hairy versions of Yoda anyway.
"That... that .... er ... dog ? life form ? what ? has just stolen my mobile phone from my jacket pocket and hidden it under the sofa !"
"Sorry, he's a Sith Tzu..... he can't resist being evil."