If you were looking for something funny to buy yourself or a friend, get to Target: they have a selection of Star Wars onesies for adults: Chewbacca, Darth Vader and a Stormtrooper.
They seem to be various sizes, and amusingly the tags say “union suit,” I guess another word for onesie. They have hoods too, and the Vader one has a cape. Pretty awesome.
