A "Mouf Piece" is not a grill, or lawyer. It is the way you can spit yo game to the females. If one does not posses this ability, then he who shall not aquire a mouf piece, shall not get laid.
Nerd: Hey, Want to go to the dance next week?
Sexy female: *Ugh* No, geek!
Mouf Piece Person: Say Lil' Momma, wanna ditch the party and head to my crib, and kick it?
Sexy Female: Helllll yeah! *pulls out a Magnum condom*
Geek Stares, and cries.