This was part of something I watched on UK television sometime in the 1980s. I can't remember if it's from a film or tv series.
There was an atomic war, however things seemed fairly normal afterwards but an absurdist society developed (I'm not too sure about this bit TBH)
Anyways, what I remember is several people meet up in a nicely decorated room, they all drop trou and sit around (on toilets) a table chatting and having pleasant conversations.
One excuses himself and leaves the room, he goes down a corridor into a tiled room and enters a cubicle. He bolts the door and then sits and eats a meal. Then washes his hands and returns to the party.