the.com/muffin top

means The roll of flesh that spills over the top of tight-fitting pants or skirts, named for its resemblance to the overflow on a baked muffin.

from A straightforwardly visual coinage from the late 1990s: bakers have long called the domed, overhanging crown of a muffin — the part that balloons out past the paper liner or tin as it bakes — the 'top.' Someone noticed the same silhouette happening at human waistlines above snug waistbands, and the slang leapt from bakery case to fashion criticism almost instantly. It's a rare slang term with a documented 'first spotted' moment, popularized through Australian and British youth slang before spreading globally, with no deeper hidden history — just an unusually accurate food metaphor that stuck.