1) A chick whose sole purpose is to satisfy a carnal sexual need.
2) A chick you sexually desire, free of any emotional commitment.
3) A chick with a good body, but questionable looks. (see beatable)
Naturally inferred, it's a chick that you intend to beat guts, beat it up, beat her guts up, and/or beat it up and skeet it up.
Peezy: "Bruh, is that yo gurl?"
Kels: "Naw nucca, she jus my beat-em-ups?"
Lew: "Fly body n'all, but dat bitch got issues."
Damaga: "Tru! But she'd make good beat-em-ups."