pig-sty, privy
圂 centers on an enclosure for animals or waste: a pig-sty or a privy. Both meanings share the idea of a confined, unclean space.
圂 combines 囗 (enclosure) with 豕 (pig), suggesting a pen for pigs. The privy meaning likely extends from the idea of a confined, unclean place.
An enclosure 囗 with a pig 豕 inside: picture a pig-sty, a messy confined space. That same idea applies to an old-fashioned privy.
For コン, imagine a pig in a sty making a contented grunt: con -> コン, like the sound of a pig in its enclosure.