A cummy farting cunt is when a guy pumps a shiela's ass full of baby batter, then she blows it out of her big fat ass hole. Nice sound effect. Also a derogatory term for a new/used car sales manager within an auto dealership by staff.
Gary goes...'did you burn that old bat on her trade?' Dave goes...'I didn't burn her... that cummy farting cunt cooked her!'