Muffin top
From Voyeurweb's Wiki about Sex
Muffin top is a slang expression coined in Australia that refers to the fold of fat around the midriff which spills over the top of tight-fitting pants or skirts on the overweight. It is slang term for an oversized belly.
I think that mental image will do quite nicely...
Also may be called a dunlop... as in "he dunlopped over his belt".
Muffin top is also a slang expression in US that refers to the effect of a too small or ill-fitted bra and/or bra cup squeezing the boob, and the overflow of breast over the top of the cup resembles a muffin top.
