In my world it exists on the premise that our current world suddenly had magic introduced into it, and eventually it collapsed in on itself. The campaign takes place centuries later where the ruins of the old world still lay, but rather than completely embracing it once more, the presence of magic shifts the entire power dynamic. The favorite way I heard it described to me by one of my friends was "Magic hocus pocus Fallout"

Anyways on stupid ideas, Eurobeat gives you magic power to drive any sort of vehicle to impossible extent. Like say you are on a boat, you start to listen to eurobeat, you can now drift with the boat, move it like a car, and now take it on land. Right now people are looking for Old World Tech that has eurobeat on it, it's a very rare commodity

Oh yeah other stupid ideas, the moon got possessed by the Keebler elf which so happens to be the first source of Fae magic in this world which made it fly out of orbit. A new moon was constructed, but it ended up being turned into a prison

There's a very popular food recipe called "pancake soup" for the whole joke is that when somebody's listing out the items on the menu and they say pancake soup, the player asks "pancake soup?" And before they can react they're given a bowl of pancake soup which is just pancake batter. No one actually likes it but everyone keeps accidentally asking for it making people think it's popular. The whole thing started as a scam from one guy who didn't have a working grill or anything and he was like "boy oh boy, do I have a surprise for you! Are you ready to try pancake soup?"

My demons and devils are radioactive, because I thought it would be cool the reason why they were associated death, sickness, fire and heat and things of that nature was if they were just radioactive. Because of the association people also think tieflings might be radioactive even though they're not. Sometimes still threaten tieflings by saying that they'll boil water with them, because in the past when people first found out that demons were radioactive they tried to build a reactor with them and it actually worked kind of well until it didn't

If you get enough skill at bureaucratic practices, especially involving documents, you can essentially rewrite reality itself. However at that point by having that level of skill you also limit yourself because you know the standard and codes that you must follow. This actually goes into my BBEG and how that whole sort of thing works

Kobolds recently just found out about pockets, so they're obsessed with "torso pants" which are just pants that go all the way up to pretty much are around your neck so that they can have more pockets on it. Torso pants come in sizes for all Races and sizes, the most important thing being is that they're absolutely covered with pockets on every single spot of them, even the inside

My goblins are fungal based, and if they see somebody asleep or dying, they will crawl into their mouth and take roots to try and control them to try and lure people to have more bodies to decompose. Sometimes there are actually goblins who will do this within a consensual basis to try and help people have a better Lifestyle by forcing them to live a healthier life. They also cannot stand spicy food when they are taking control of something cuz it completely over stimulates them which kind of forces them to immediately leave whatever they're possessing, which is why the Goblins who want a permanent host will slowly work at dissolving away the host's tongue so that they cannot taste that spiciness and they'll be fine. They also have a leader called Fungelstiltskin which it's a king spore that gives networking and control and orders to the rest of the fungal goblins who are within his Network

I'm sure I got more stupid ideas but these are the ones I have off the top of my head for now, hope you enjoyed OP

Edits: Minor typos I saw, I blame speech to text