Okay, this is worth a second dumb Sims post in one day.
So I'm playing a house based on
these plans, and the ground level doesn't have any rooms except for a completely enclosed area in the center that just supports the house proper. I stuck some cheat objects inside of it, because I can get in there even if my sims can't.
Then I clicked down a floor to get in there to use one of those objects and found

a half-dead cafeteria worker passed out in his own filth.

Somehow this guy got into a completely locked room, long enough ago that he's very nearly starved to death. For... a day? two? he's been wandering the doorless, lightless concrete cell in which he finds himself, probably screaming for help, and wondering, as the hours tick on and the madness grows ever closer, why no one answers. He can hear the sounds of life above him -- footsteps, children laughing, voices raised in animated conversation -- but the darker shapes in the blackness are closer, and ever more numerous, and they whisper to him that this is no longer his world. Yes. Yes, he nods. There is no more light or life for him, not anymore. The dark is forever, and it has taken all that he was.
...
Or, y'know, I stuck a door in a wall and let him out so he could escape without dying and ghosting up the place. Whichever.
(Pretty sure he fell victim to the bug where your sim is talking on the phone with someone and they hang up and the someone is teleported to your lot for no good reason, because he's a household friend and he did call the house recently. It's just... usually they don't teleport into a doorless chamber.
He's lucky he didn't wind up in the cowplant pen out back.)