fuhtass is a nice way of telling a girl she has a big butt, with an accent. Which makes it seem less as bad. Or from a coach's point of view, can be a lazy player. A fuhtass may need to lay of the hot cheetos and hit the gym up more, but still have a pretty face.
That bad ass softball player, has a fuhtass.
That player needs to get her fuhtass quicker around the bases.