How's This Possible?

Admittedly, I HARDLY have boobs and have to always pin my button downs. I mean, WHY can't they create a button down that actually just doesn't pull- and fitted button downs, not these gigantic/boxy ones. Mariah Carey must either get them custom made or gravitational forces don't apply to her, because despite her rather "robust" chest measurements, the button has not popped. Granted, it may snap any moment... but really, how is this possible??

Of course, the guy in the background is STARING like it's his job... what a goomba.