I've heard muffin top, but not cupcaking. And the bra thing I've more commonly heard as "quadraboob" (when the cup cuts each side in half . . . yeah, y'all know what I mean!)
I've definitely heard quadraboob, too...that's the same thing as cupcaking as I described, though I've heard the bottom half (tight pants) called cupcaking and the top half (quadraboob) called muffintopping...I guess it really just depends who you talk to, but we all get the same general idea from it.
I always thought the top bit was called "Rushmoring." I wonder if that's more of an Upper Midwest of the US thing?
** Sorry I messed up the quote tree!