A "kick 'er to the curb" kind of gal. Someone you've had your fun with, then thought better of it. Low-life bitch. Worse than a regular, "Pig". Someone who crawled out of the gutter. Someone not worthy of your association. The girl that wronged you, and then moved on to a better life, while leaving you in the ashes.
I'm not hangin' out with that "Ditch Pig". I'd date her if she weren't such a "Ditch Pig". We had a good time, but that's all it was, 'cuz she's just a "Ditch Pig", and she'll drag me down.