This has happened for real. This guy forgot his password and lost Bitcoin valued at over $220 million dollars.
This guy offered the city where he threw a flash drive away $70 million to help try to dig it up in the city dump. Talk about a very expensive needle in a very large, very smelly haystack.
Being trapped in an elevator either with a very pregnant woman or two characters that were at odds with each. I know there was an All in the Family episode when Archie gets stuck in a elevator with a pregnant woman, and another episode where he got stuck in the basement with Meathead.
Some examples of previously mentioned tropes in the Brady Bunch:
Peter had a twin in one episode (but not sure if he was evil)
Bobby dumped a box of detergent in the washing machine
Bobby and Cindy attempted to get a World Record for riding a SeeSaw.
I really hope I never see another plot where the main character is tasked with taking care of someone’s beloved pet, only to have it die or escape, and they try to replace it with a matching impostor.
The corollary to this is accidentally losing or destroying a precious object with which someone has been gifted or entrusted and they trying to replace it surreptitiously so the other party won’t realize what a klutz they are. This can be done by buying an exact copy (like Ann’s diamond earring from Donald in That Girl) or having one made (like the heirloom brooch in the shape of the USA that Rob’s mother gave to Laura in The Dick Van Dyke Show).
Of course, the truth will come out in the end and everyone will have a good laugh over it. 
The version I saw is someone is given/borrows something “irreplaceable” from someone, accidentally breaks it, spends the entire episode trying to fix/replace it, but then at the end of the episode after learning the truth the original owner opens up a closet and shows off they have dozens of the “irreplaceable” item and you find out that “irreplaceable” simply meant in terms of sentimental value not that it was literally one of a kind.
Of old??
I just saw that on a new Brit cop show- Cuffs.
Esquire just suggested this. 
Ie a Gentleman lights his lovers cig after sex, iirc.
As a volunteer ranger, I used to see that at least once a week.
Indeed, there are, as any D&D expert will tell you.
The Jann is the least powerful and the Marid the most.
If it is a goldfish, it can work, otherwise no.
But they just did this with a bird in All Creatures Great and Small, and it worked out.
Variations on the theme include the gifter and the giftee both buying a replacement without telling each other and then planting them where they’ll be “found.”
Of course, it never works out the way they want it to and desperate confusion ensues.
Pretty sure that story is in the original 1973 book. There was a twist in the book in that the old bird had never made much noise, where the new one was singing and chirping all the time. The owner was very happy that the bird was apparently feeling so much better.
De Maupassant
That’s what I thought of.
There’s a commercial from this year with a spit take, and even worse, it has the “standard” disclaimer, “Don’t try this at home. No actual spit was used” or similar.
When’s the last time one of the characters tried to go on two dates at the same time, resulting in wacky hijinks? Especially if one date was formal and one wasn’t, requiring frequent changes in clothes, ultimately resulting in a mishmash of outfits?
Or the neighbor volunteers to take care of the other neighbor’s cat, which runs away, so the neighbor finds a “exact” duplicate somehow. The owner show up, hugs “their?” cat just as the original cat strolls through the room. Done on many many sitcoms.
According to TVTropes the answer appears to be Never Have I Ever, from 2020 or 2021. I don’t think tropes ever retire, they just fade away.
In an episode of The Dick Van Dyke show, Don Rickles plays a crook who holds up Rob and a pregnant Laura in an elevator, which then gets stuck. (Working from memory here, so don’t quote me.)
Or, jumping off from this, the pregnant woman gets trapped somewhere just as she goes into labor, and some random person with no medical training has to deliver the baby. Even Star Trek: TNG did that one for God’s sake.
The “Trapped in an Elevator” trope was once used ro resolve a cliffhanger in Dallas. It gave JR and Bobby an opportunity to air their differences and reach an understanding while they drank a whole case of wine overnight.
Of course, this raised the obvious question of how they were going to relieve themselves until help arrived in the morning. The writers solved it very cleverly by having Bobby force open the doors as soon as the elevator stopped moving, which gave them the entire shaft to pee into.
You can also just pee into the bottles since you’re going to have to keep the bottles around anyway, and if you can still cap them you won’t have to deal with the pee stretch that would happen if you just peed out the elevator doors.
I’m guilty of using this trope once on an in-office meme of Jared Kushner passed around management and executives.
Try peeing into a wine bottle while I’m half drunk? I’ll pee into the elevator shaft, thanks. The janitor can clean it up in the morning.
Besides, there are only two of us, and the bottom of the shaft is a long way away. I don’t think odor will be a problem.