Weightless astronauts often sit, stand, walk, or sleep on (or near) surfaces that (with gravity) we would normally call walls or ceilings. I reference such a phenomenon in my comment here:
I would also add that the bulk of the CSM flight was in weightlessness, which allows astronauts to reside in places and orientations that are not otherwise convenient. (Shuttle astronauts also took advantage of this.)
Is there an accepted name or jargon for this activity?