When planns go wrong

I love to read and also do roleplays where plans go wrong. There is 2 story lines that come to mind.

First one.... Siblings best friend and the other sibling go to take a trip together where things go wrong. Like they book a cabin on a remote lake that should be a 2 bedroom one and the company books them into a cabin that has only 1 bed and its in the living room where its meant to be a solo cabin or a couples cabin. Now they are forced to sleep with someone they known and grown up with for years...

Second one... 2 strangers get booked in the same room. Normally when I hear of this kind of plot its 2 kids (18 years olds out of the house for the first time) and they get a surprise. The surprise is a roommate is of the other sex, and cant get new rooms as the college is booked so the 2 shy normally virgins who never was good with the other sex is forced to live with not only the other sex but now a stranger.
A few times I have seen like a hotel room/resort gets double booked and both show up for there reservations.. That story line always seamed a bit to far fetched but could work..

What about a small town jail that only has one cell?

That could be interesting too.

Man and woman, strangers, are booked into the same cabin or cell or whatever. They try to maintain some privacy but become intimate... and then find they are long-lost siblings or parent-child.

Gimmick: A small-town constable's game is locating unknown relatives (online tricks, sure) and jailing them in the village lockup's single cell. With one bed. With a hidden camera. For lulz, or to blackmail them with evidence of incest.

Let's scale that up. A global network of evil university admissions officers crunches Big Data (including DNA) of all applicants, seeking unknown relatives to be roomed together. Why? An evil plot, sure.