Typically used with the preceeding pronoun "her", a metaphor used when having sex/nailing/fucking a girl (commonly referred to as a
slut, hoe or bitch) so vigorously that you could visualize splitting her in half up the centre (or up the back, respectively). Usually referring to a slim tall girl, or a cute, tiny petite
one.
Often used in the degrading sense by a
male among his peers to raise his esteem.