A synonym for male genitalia, most commonly used by a bull in Lower Manhattan and Brooklyn. It was derived from the word jawn after growing in popularity as a term substituted for every word that one couldn't creatively think of by himself. Soon, "jawn piece" became a more street-friendly description of one's package.
"I slapped that slut in the face with my jawn piece."
"Gay bulls keep starin' at my jawn piece."
"I was at the bar and this whore grabbed my jawn piece"