also known as B*muff, the muff, the muffinator, muffin, muff, ect. One of the coolest muffins around. Generally found in the wilderness, this particular muffin is also known as the dark lord. even better than blueberry.
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."