The act of sticking your penile organ between a woman's (preferably lubricated) buttcheeks, followed by her jumping up and down, until the recipient's orgasm is achieved. Also known as "hotdogging". The "Z" is open for interpretation and dialogue.
Yo cuddie, that skeezer is good for nothing.
Nah cuh, word on the skreet is that she gives a fierce Z.J.