Why does my ball sack bacteria choose to take up residence in my fat folds instead of my crotch?

the bacteria spawned from the sweat of my ball sack aren't content to stay there but seem to migrate to the various folds of fat in my american belly. There within the folds of my american fat they seem to have a veritable garden of eden to live in but why aren't they content to stay within the ridges of my ball sack which must be like mountain ranges to them? Why do they desire to leave my ball sack and reside within the folds of my fat american belly instead?