But some of them blow it because they can't control their reactions to their good fortune. It all turns to shit and their life is therefore more crappy than it would have ever been if they didn't have that really good luck happen to them in the first place.
Someone like that is a shitbritches.
the origins of shit britches are debatable, but it most likely came from prison punks (aka. prison bitches) providing easy access to their cellmates for some instant romance. chicks don't usually think shit britches are sexy so it really amounts to a form of fashion that guys wear for other guys.