The spectrum by which a girl's body is rated in comparison to her face, where butterface is an ugly face v a nice body and scuffin muffin is a nice face v an ugly body. A zero is optimal, denoting your body and face are roughly at the same attractiveness level.
Guy: "Ehh I'll give her a overall 7.5 on the hotness scale, but on the Butterface-Scuffin Muffin Spectrum (B-SMS) she's moderately leaning towards Scuffin Muffin."
by Cunty Punter October 16, 2010