snack-piece
A vagina. Usually one that is young, fresh and nubile.
"Hey girl, let me get that snack-piece! I know you got it on ya!"
3 piece snack
A decent athlete - bball, boxing, that's got skills but put on a few pounds and can hang for a couple of rounds before being schooled and looking very winded.
Look at ole 3 piece snack going down in the third from an uppercut.