Why I outta

Where did the phrase "why I outta", slang for "why I aught to", come from?

I've heard it said in old movies. I'll check my catchphrase books and see if there is a particular movie or character associated with the phrase.

Actually it's "why, I oughta--", from "why, I ought to--" and the physical threat goes unspoken.

The construction is called an aposiopesis, which arises when the 'if- clause' or protasis of a condition is stated without an ensuing 'then- clause' or apodosis. [Source: Wikipedia entry for Aposiopesis]