@ SVU~freak - my bunny used to sort of do that because she wasn't strong enough to flip the litter box over she just dug half the litter out a did her peeing out of her litter box, I got quite frustrated cause I had to clean her cage right after school , so I asked and some people said that she may not of been getting out enough to exercise, so I started to keep her out more and for a longer time and she stopped so that's how I fixed it.
Also I use Eco Litter (Its cat litter by the way), only because there is no rabbit litter there and Sugars breeder uses it so I decided to use the same.