An unknown person: “Whosy-whatsy.”
Violence on screen: “Buckety-blood”.
We actually have an honest to goodness pancake turner in the kitchen. It’s like a spatula, but bigger. No, we didn’t just nickname a big spatula, that’s what it was sold as. Only had it a year or so.
we call it an egg lifter
In my family, the very back seat of our station wagon was the backety-back. That was the seat where you actually faced backward toward the rear of the car. I haven’t heard that particular name for it anywhere else. Once we upgraded to a minivan it became the wayback.
My mom called it a jockeybox.
We just called it the dash. “Get the map out of the dash.”
I only went to undergrad there, but I was under the impression that the popular term was “jaggerbush”. 
My family called the third seat in the station wagon the “all-the-way back”.
The crust between your toes? “Peanut butter and jelly”.
Changer in my house. Especially since it was to the cable box, and thus could only change channels.
Turn signals are “blinkers.” Flip-flops were thongs for much longer than they were in the rest of the world. And the wash cloth is a worsh-rag.
Also, while we didn’t have one, a den was an extra room your family normally used instead of the living room when by themselves. The Living Room was for entertaining guests and had to be spotless in case anyone came by. To have this arrangement meant you were well-to-do. Or you didn’t have many guests stay the night, and didn’t need a spare bedroom.
Our family always called the living room the front room. I think a lot of people did during the 60’s and 70’s, but i remember pronouncing it like it was one word. frontroom.
My dad had weird names for stuff and one I can remember now is he called coffee fracka. I don’t know where it came from or what it means.
So does my dad (grew up in country Victoria). We just used to call it a ‘flipper’.
My wife’s family calls the remote control a ‘console’.
When I was a kid all the really sharp paring/utility knives had dark wood or black plastic handles while the regular butter knives had white/yellow bone handles.
So if we wanted a sharp knife to cut up a piece of fruit we would ask for a ‘brown-handled knife’. I still do that on occasion.
Computer: “comp”
Spaghetti, but with mac noodles: “scattabuchi” (I’ve gotten quite a few raised eyebrows from outside the family on that one)
When SWMBO was growing up, her family had one of the early mechanical remote controls for the TV. It made a strange. metallic sound when you pressed the buttons and they thought it sounded like “poo-kah”. To this day, she calls the remote a pookah, even though we have one that controls everything imaginable electronically. I could probably program it to open the garage door. But it’s still a pookah.
It ain’t that common in Kentucky; I’ve lived here all but three of my 37 years and have only ever heard that usage once, from my husband’s grandmother. (And I assumed she was talking about real mangoes, so it was a mess of a conversation, and then his whole family looked at me like I was the nutty one.)
Of course, I’ve lived most of my life in the flatlands, and there are lots of little terminologies up 'round here that initially threw me for a loop. Things like putting your clothes on racks instead of hangers or pushing a buggy instead of a cart at the store, or the main end of something being the very end, and when something is unpredictable or unforeseeable, it’s untelling how it will turn out. And people around here don’t “go to the Chinese/Mexican restaurant” or “go to [insert name of ethnic restaurant]” or “go for Chinese/Mexican” or “get Chinese/Mexican,” they “go to Chinese/Mexican.” If you didn’t know better, you’d think there were actual restaurants here in town named Mexican and Chinese.
Waybacks and sticker bushes are perfectly cromulent terms. But using toasted cheese and grilled cheese interchangeably is just plain wrong. There is toasted cheese, and there is grilled cheese, and never the twain shall meet. Toasted cheese is a single piece of bread with cheese on that’s been put in a toaster oven or broiler until the bread is browned and the cheese is melted. Grilled cheese is a closed sandwich, with butter on the bread, cooked in a skillet until the cheese is melted and the bread is a soft golden brown.
While growing up, we called shopping carts like the one pictured below “bundle buggies”.
I still have and use a bundle buggy!
I had a deluxe four-wheeled bundle buggy, but Mr. Daynet recently broke it, so now I have to make do with a two-wheeled version.
We call our basement “the cave”. We picked that expression up from a landlady we once knew.
My family seems to be the only ones who call duct tape by its proper name: Grey Tape.
As i raised my kids to say the correct name, my wife has become a convert to the grey side.
Have they seen this episode of the Paul Reiser Show?
My mother calls advertising circulars “throw aways”. for years I thought that was what they were called. I’m sure advertisers wouldn’t have appreciated that.
As I’ve mentioned many times before here, thyere’s a whole book of these out there – Paul Dickson’s Family Words:
The earlier of the two kinds with pictures linked-to, above – which is the kind we had at home – was called by my mother, a “fish slice”. This was in the midlands of England, 50 - 60 years ago: I’ve never heard this expression for the implement, anywhere else. My using it in later times, occasionally caused confusion between me, and folk who hadn’t heard the expression, and thought it implied that the thing concerned was specifically and only for use with fish – analagous maybe, to AliveNot’s thoughts on the term “pancake turner”.
I thought about this thread last night while fixing dinner. In our house, Uncle Ben’s Long Grain and Wild Rice is “bug rice”, because the kids used to think it looked like it had bugs in it. The name stuck.
At the other end of the spectrum, my coupon-clipping ex-wife used to call all the stuff in the middle of the Sunday paper the cream filling.