A muffin-top is the phenomenon of overhanging fat when it spills over the
waistline of pants or skirts in a manner that resembles the top of a muffin
spilling over its paper casing. Muffin-tops are generally considered
undesirable.
Muffin-top originated as Australian slang in mid-2003, but has since become
popular in other English-speaking countries. It may have been first popularized
by the Australian television show Kath &Kim.