A girl who has to try really hard to stay somewhat in shape because it's the only thing she has going for her due to the fact that she's a total cow (i.e. conniving bitch, undercover whore, etc.).
Generally, this girl has little to no friends because people either just don't like her or after getting to know her would rather just hit it and quit it. And those she does have are absolutely oblivious to what a bitch she really is and let her walk all over them.
So be cautious of what you tell a skinny cow, because she'll use it against you at any time to make herself seem like the victim in any situation after you've realized what she truly is. And that may just come sooner than later because she uses people, once she gets what she wants she'll drop you like a hot potato. But if you're the only one around to hang out or to give her a ride somewhere, she'll be blowing up your phone!
Person 1: Who just text you?
Person 2: Skinny cow, she must be having troubles with her other friend and want a ride somewhere.
Person 1: Yeah, well, whats new?