When I was young, I (apparently) pronounced “Denver Broncos” as “Dipven Doncos” and the game of Croquet as “O-crow.”
Mine was “Dine-cano” - meaning either a volcano or a smokestack that spewed black smoke.
I was heavily into Dinosaurs at age 4-5, and read a bunch of kids books about them. One thing that kept popping up in all of them was the theory that a massive volcanic eruption was what made them go extinct. Dunno the current theories, this was back when I was a little kid in the mid-80s.
But regardless, I formed a connection between “dinosaur” and “volcano”, and to a lesser extent a smokestack (the kids books always had an illustration of an erupting volcano spewing flame and black smoke)
So “Dinosaur” + “Volcano” became “Dine-cano”
My morning commute to the babysitter when I was that age went past a small factory that had a large smokestack, always blowing smoke. I can remember pointing this out nearly every day - “Look, mommy! That’s the Dinecano!”
Mom reports that she remembers this (and the factory, and smokestack is still there) and also that she figured out why I called it a “Dinecano”.
Cow = pig? That’s not mispronounced, that’s just wrong 
I’m an old woman and I still say “skizz-ORs” for scissors.
Very true. It was a stab at “humor.”
My eldest nephew called Christmas lights “Adeeps”. Took us a while to figure that one out - we would point out houses all lit up and say “Ah, pretty”, which became adeeps. To torment him, I tried to get his youngest daughter to start calling Christmas lights adeeps: “Auntie, doze are Kissmast lights. I knows better!”
TheKid tended to call our great Mississippi River “Missapissy”, the hospital was “hop-it-all”, and my nephew Joey was “Bow-ee”. The family still calls him “Joey-Bowee”.
Par cark.
Buhsketty.
Snizzors.
My sister liked those inflatable toys, baboons.
When my daughter was pre-school, she pronounced penguin very close to “pink one” and it took me a while to figure out what pink thing she was talking about. She also said “airplane” oddly, losing the “p” and substituting an odd guttural sound. Fortunately, she talks real good now! "D
My daughter pronounces “little” as “yittle”
“Twinka Twinka yittle stah, how I wonda what you ah.”
When my son was little, instead of calling his grandmother “Grammy” he’d try to say My Grammy and it’d come out sounding like “Miami”
Naked as “nake+d,” (rhymes with “caked”). Whoops.
I think, funnily enough, I also mispronounced “mispronunciations” as “mispronounciations.”
nakkin(napkin)
drawl(draw)
testicles(tentacles) I remember that instance very well.
Driving to Barcelona to see my grandparents, we crossed this town called Tudela, which I misinterpreted as tu dela, that is, your dela. I asked what a dela was and whether other people had delas too, since this one was my dela. Eventually my parents stopped laughing long enough to explain that it was one single word, but I still wasn’t convinced. Once I’d learned to read, they pointed out the lack of a space on the signs. That convinced me but dangit, it was so nice, thinking that there was a place that was mine, even if I couldn’t do anything about it.
We moved to Tudela about one year later - and we still call it Midela among us sometimes.
My daughter: Elevator=Alligator. So now we all go up and down in the alligator.
Well, since it’s changed into cutesy mispronunciations from other than one’s self:
When my 2YO granddaughter was first starting to use actual words, she would refer to a dirty diaper as “bug-ah,” accent on the second syllable. Everyone was mystified as to where this came from, but gleefully starting saying things line “Oh, buggah!” instead of “Oh, shit!” Her aunt figured it out fairly recently – the toddler was trying to say “garbage” and was reversing the syllables.
Which leads to the story I really wanted to tell: People were referring to me as “Grandmom.” But to the little one, I am Maga. (Rhymes with “buggah.”) Which I find adorable, of course.
Similarly, when she was growing up, when we told my baby sister we were going to Myakka Park near Sarasota Florida, she said “But I don’t want to go to your akka, I want to go to my akka!”.
Doug Hunts=Doughnuts
My niece thought I lived in “Cheese-cago” when she was a toddler. Also, my sister referred to pizza as “pie-tzee”.
I thought Alzheimer’s disease was “Old Timer’s Disease.”
My cousin pointed out the car window at the flying things & said ‘damburs’ (one word). No one could determine what this was. Eventually figured out that those things with feathers that fly & leave white droppings on the car are ‘damn birds’ (two words)
My mother used to say Hackenhack for Hackensack and of course, pasghetti…
The 2 things I used to say were: eyebrushes instead of eyebrows…don’t ask me how I got that…I remember asking my aunt why she drew on her eyebrushes
and the other one was that I was visiting family down in Florida. Their last name was Kovar. Pretty easy to say…Koe-vahr…not to me…this was my great aunt and great uncle…I renamed them…Grandma and Pop-Pop Joey Cold Water!!! 
I love learniversity, because it is. My older son used to call people “income poops.” Maybe some of them were. 
This is stretching “childhood” a llttle, but try saying “metabolism” with the accent on the first syllable, like I did. :smack: