Cardi B is getting the royal treatment -- Stefon Diggs hooked his lady up with an entire castle for their vacation in France ... where they'll be able to eat, sleep and poop like King and Queen!!
The rapper shared a tour of the temporary digs on her Instagram Story ... and the place comes complete with a moat, dining hall, indoor pool and themed bathrooms!!
Launch Gallery Launch Gallery During the walkthrough, Cardi cracked a joke about the toilet -- which looks like an elevated hole with a lid (don't worry, there's actual plumbing) -- saying, "this is where we take the royal s***" before panning to the tub, which is "where I will wash my royal hiney.