Two phrases I can think of when I owned an interior store " One stop shopping" and “One call does it all” I have had several people tell me I did not come up with them but I still think I did. This was early 1980’s.
When my boss was over- (and I thought insincerely) praising my work, I said “Save your butter for your toast.” Very off the cuff. She liked it so well she put it on her board o’ quotes. (And if my former boss is a participant here, I have now thoroughly and unequivocally doxxed myself.)
I just googled that and nothing came up, so it appears you did make that up. Nice, I like it!
Now go post in “Sayings or phrases you thought you made up, and it turns out you actually did”. 
Before long a Google search for that phrase will lead folks back here. Since the only ones likely* to research that phrase are former co-workers, they may start reading my old posts, and then I am well and truly cooked.
*a relative assessment, still very unlikely.
1978’s, “Dawn of the Dead,” uses One stop shopping somewhere in the middle; Roger says it to Peter when they’re taking the grille off the vent in the elevator shaft.
Sadly, I didn’t need to look that up–IT’S STUCK IN MY HEAD!
I know my nephew invented “pleather” in the late 70s. I know it!
I was using “underwhelmed” long before anyone else was, which I see now was used at least as early at 1949. Oh well, I’ve still got “coolth!” 
What? That’s been around since the 1500’s?!? Dammit!
As a teacher, I’m always looking for ways to Almost Swear.
My students have picked up “Qua la fuque?!?” from me. The “FOOOOK” gets lengthened in proportion to the absurdity of the situation.
…
(But if I could think of it, I’m sure others have, and are probably getting rich off Q la ƒ merch)
Already happened to me. If you google “Roller bullfighting” (I think I was suggesting a dangerous sport) hit #2 is me on these very boards. There appear to be only 2 hits for that phrase - one on Facebook that I can’t date (because I don’t know how Facebook works). So the jury is still out on whether I meet the terms of the OP.
j
Perhaps we need that thread? So far as I know I originated the phrase Fair Weather Steeplejack (sometimes Fairweather Steeplejack) - no hits on google for either. Used as a derisive description of the actions of someone who is far, far braver than you are.
(It dates from the early weeks of lockdown. Absent any other task remaining to be done around the house, our neighbour over the way decided to pressure wash his roof (don’t ask); spent days up there on a wet roof, staggering and slithering around with no safety equipment. But where was he on the day when we had wind gusting at 40mph? Nowhere to be seen, that’s where. Hah!).
j
Here’s one from a friend I shared an apartment with circa 1975:
He used the word “humongous” regularly. I had never heard it elsewhere at the time, and I don’t think it was in common use. Shortly after that, we both began to notice the word being used a lot. My friend was surprised. He thought he had made it up.
Here’s something loosely related: When I was quite young (think, 1960’s) my father occasionally used the word “keister” (spelling apparently not standardized) meaning “ass”. (Occasionally he pronounced it “kazeester”.) I never heard that word elsewhere before or since until early 1980’s, when President Ronald Reagan occasionally used it. After that it became slightly more common – I guess people picked it up from hearing Reagan say it. I have no idea where my father got it from.
In Hebrew, there’s actually a word for that. “Machar” means “tomorrow”. “Machartaim” means “day after tomorrow”. It can be understood as the word for tomorrow with the suffix meaning “two of…”, or “a pair of tomorrows”. Strangely, there is a word for “yesterday” but no word for “day before yesterday”, although such a word could readily be constructed the same way.
There’s a story related to that. In the 1960’s through 1980’s, there were numerous research projects attempting to teach some rudimentary language to various animals, mostly chimpanzees. OTOH, many other researchers in psychology and linguistics were very skeptical of this. Since chimpanzees can’t learn to talk, some form of sign language was commonly used.
So this chimp (I think it was Nim Chimpsky, one of the more famous ones) was out for a walk in the park with the trainer, and the chimp was making hand signs for various things that he saw. When they passed a pond with a swan in it, the chimp made the signs for “water” and “bird”. Get it? Waterbird!
The trainer thought this was a major breakthrough! The chimp demonstrated that he actually got the concept of inventing sensible words or phrases for something he had never actually seen before!
The skeptics were, like :Insert Roll-Eyes Here:. They argued that the chimp was just randomly making signs for things he already knew. He saw water so he signed “water”. He saw a bird so he signed “bird”. No indication that he was actually inventing a new word or phrase.
The whole debate over whether chimpanzees were ever actually learning language, grammar, and syntax, or whether they were just learning phrases in mindless imitation of their trainers, went on for years before people finally lost interest.
(I worked on a project that was teaching some elements of language to dolphins, so we discussed stuff like that a lot.)
That’s really cool @Senegold, I’ve always been fascinated with experiments in which animals are taught elements of language-- Koko the gorilla and Alex the gray parrot are two intriguing examples for me. Koko supposedly saw someone wearing a ring, and not having been taught the sign for that, called it a “finger bracelet”. And she named her pet kitten “All Ball” which is freakin’ adorable.
Please share some of your dolphin language experiment stories if you feel like it.
The staff (mostly grad students and low-paid student assistants or volunteers) were encouraged to interact with the dolphins in between training sessions. Many of the staff went swimming with them on weekends. They loved to play catch with volleyballs (tossing and catching balls between themselves and the people; only rarely between themselves). They could toss frisbees with surprisingly good aim, but I never once saw them even try to catch one.
The tank had wooden railings around the rim ( visible in this photo ) . The wood, being constantly soaked with salt water, had gotten a bit soft and mushy over the years. Eventually, the dolphins discovered that they could bounce on the railings. So they spent all their free time jumping out of the water onto the railing to bounce on it. Need I say that one one day, one of them fell out of the tank onto the surrounding concrete deck? Then we had to haul out the stretcher, go out into the adjacent boat marina and round up four or five people (or one Samoan, as we always said) to get the dolphin onto the stretcher and back into the tank. We had to replace the railings with newer sturdier non-bouncy planks to put a stop to that.
One afternoon, just for grins, one of the trainers showed one of the dolphins how to twirl a frisbee on its snout. They must have thought that was a big kick, because they then spent their entire evenings and nights for the next several weeks twirling frisbees on their snouts, until they eventually got tired of it. (The other dolphin quickly learned it just by watching the first dolphin. They are very imitative.) Then they started putting the smaller frisbee inside the larger frisbee and twirling them both at once.
The water was pumped from a 40-foot deep well just outside at the edge of the surf, so it was extremely well filtered of particulates simply by passing through all that sand. That’s why the water was always so crystal clear. It was constantly being changed too. The pump continually pumped clean water in, and there was a big drain at the bottom of the tank where water continually flowed out into the marina.
One of their games was to put a frisbee over the drain so the tank would fill up to the top and overflow. Then they swam at breakneck speed around the edge of the tank, deliberately creating huge waves that sloshed over the side.
ETA:
For our research report on Language Acquisition in Bottlenosed Dolphins, see:
(This page is just the abstract. You have to pay to get the whole 80-some page article, or find it in an academic library or somewhere.) Note the list of acknowledgements at the end of the abstract. Yes, one of these names is me.
You might also be interested in this article by Irene Pepperberg (of Alex the Parrot fame):
I am pretty sure I independently invented the aphorism “it’s nice to be smart, but it’s smart to be nice.” However, a Google search suggests that I’m either wrong or I’m not the only one to come up with it. (It is kind of obvious, rather like “working hard, or hardly working?”)
On the other hand, I’m sure “If I waited for memory to serve, I’d starve” is original with me. Not that it has caught on - I’m the only one who says it.
Not me specifically, but I was convinced I and other members of my college gaming club started using “toast” to mean “you’re screwed.” I’d never heard it anywhere else, and we used it quite a lot back in the early to mid '80s. I was surprised when I started hearing other people in other areas (and even people on TV) use it. I guess somebody in the club must have heard it somewhere and used it, and I just assumed it was ours because it was new to me.
Does this mean you were actually working with Louis Herman?
As a young(er) biologist, I devoured everything Lilly and Herman wrote on their dolphin work, and got to meet some of Mr. Herman’s students and grilled them about living alongside tursiops…
Here is Herman’s advice to “young(er) biologists”…
(Sorry for the fanboy hijack; this should probably be a separate AMA thread…)
Hi, digs. I tried to PM you, but stupid Discourse says you’re not accepting private messages at the moment.
(How does that work? Can I send PMs only if the recipient is logged in? Or does the recipient have to enable PMs or something?)