An extremely dirty or vial slut that will never be a swan. The "smut duck" usually takes advantage of the drunkest guy(s) at a party. A.K.A. mud duck(hideous female)..... however dirtier(ie. taking it in the ass).
After the act of intercourse in a heterosexual nature, while a woman is menstrating, the mixture of the male ejaculate nd the womans exploded ovary results in the resembling of the sheets to the components of a pizza.
Man, my girlfriend was on her rag and left some serious pizza sheets.