Or if you have younger children how do they speak? Here’s some translations of mine when I was little:
Boshtrosh (or something similar) = to go underwater
Crash can = trash can
Hawkenshpeef = leaves (I made up some weird stuff as a kid)
Mershacul = commercial
Oshkoshmagosh = overalls
Schmell = smell
In our church’s “back room” there was a Wurlitzer piano, and for years I called it the “Twinzinger” piano b/c of those Twinkies knockoffs called Zingers. “Wurlitzer” made no sense to me, but “Twinzinger” did.
FTR, though, I find it amusing that according to my mother I was not a talkative child at all; at an age when most kids are trying out words, I did my very best to avoid verbal communication. If I wanted it, I pointed to it. If I wanted the closet opened, I’d bang on it. Pitching a fit, if necessary, until somebody went to the trouble to figure out what I wanted.
And yet I grew up to be an English major and the kind of gal it’s very hard to shut up.
One of mys siters said “bacon birdies” for butterflies. She got that it was named after a food and a flying thing, just not the right ones.
My other sister said “figlet” instead of foal…there was obviously some confusion in her mind between foals and piglets.
One of my cousins recently went through a stage of asking for ‘Cock Porn’ at the cinema…
Oranges were “Ontants”, and apples were “Mopmoes”. And hedgehogs were “heggiedoggies”.
I don’t know what I did when I was a child, but my sisters are quite a bit younger than I, so I remember when they were children…
ovill for olive
sank for snake
poe-doo for pillow
shoppin for shot (as in vaccination)
When I was a child, the plural for eyebrows was eyebrown. You have one eyebrow, and two eyebrown. I still say it sometimes. Elbow was elbogen. Grilled cheese was drilled cheese.
My daughter had a few when she was younger too. Baskets were bastiks, onions were unguns, remote was just 'mote, water was yadder, and everything below the waist and above the knees was your butt.
I did not use any fun words, but my younger sister had a few:
NooNooNaNas was the local Golden Nugget restaurant
Her blanket was her stinky (That I can’t explain. It was clean!)
Grapes = Bloo Bloops
I liked her word for grapes, I still use it I mean, they just look like bloo bloops.
“Seebee” for hair clogs in the bathtub drain, which I found terrifying.
I used to think “vocabulary” was pronounced “vock-you-bullery.”
I was just re-reading a diary I kept for two years when I was eight and nine respectively. The spelling wasn’t bad, but the grammar sucked. I seemed to have had particular trouble with adverbs. (I guess Lolly-Lolly-Lolly never made much of an impression.) I did call my girlie little classmates by their last names; but we all did that at that age. Other than that, I pretty much spoke like an adult. We never had cute names for stuff in our family; my folks were into children speaking clearly and understandably. That kind of stuff wasn’t cute to them. Thus, no “pasketti”, “poo-poo”, no mispronunciation of people’s names, etc.
What can I say, I was raised by neo-Victorians! 
I was another who didn’t verbalize early. I knew I could, but it never came out right, so I wouldn’t talk.
I also learned to read at a very early age, so I had a lot of mispronuciations of words I’d only seen in books, but never heard out loud. When I was very young (maybe 3 or 4) there was a piece of paper on our fridge with a grocery list or something on it. On the paper was printed a man with his head stuck up his ass. The caption read “Your Problem is Obvious”.
I went to my mom and asked “what’s o-BIV-ee-us”? It took her a while to figure out what I was trying to say. This kind of thing happened all the time.
According to my Mom, my kids mispronounce the same words I did when I was their age. (Whether it’s genetic, my Mom’s full-of-crap -or- just a coincidence is anyone’s guess). The 1st that come to mind:
Piss-ghetti: But who hasn’t?
Lie-berry: Library
Pick-tra: Picture
My favorite mispronunciation of my daughter’s is Hice Cream. She says Hairplane, too.
A lot of her ‘w’ sounds come out as ‘v’. Vindow. Vun. Vant. We’re not sure where the German accent comes from.
I never thought I’d be the type of person who thinks her kids’ mispronunciations are cute (those people seemed like an annoying lot to me), but I do. In fact, I have to struggle to actually teach her to say the words correctly.
Now, if you’ll excuse me, I vant to get vun hice cream cone.
Alias, my four-year-old daughter calls them “eyebrowns.” She seems to have made the connection between “eyebrows” and the color brown while watching me or her aunt put on makeup, so they’re “eyebrows” in their natural state, “eyebrowns” after brow powder is applied.
I don’t recall any specific mispronunciations of my own as a child, but one of my cousins misheard the phrase “night-night” as “Nick-nock” many decades ago… Yeah, there are people with children and grandchildren still saying “nick nock” to one another.
I still say that. But that’s showing the yokel influence of these parts of the world 
My friend’s daughter was calling her stuffed polar bear a “roller bear.” When my friend corrected her, she looked at her mom like she was nuts and said, “No, it’s a roller bear, 'cause it rolls around in the snow!” She’s funny. She’s one of those kids that makes up all sorts of weird combination words…I wish I could remember more of them, because she has a million.
My boy is just starting to talk. He says p-apple for pineapple, bubberfly for butterfly…and, that’s about it. He’s surprisingly precise about the few words he does say.
I don’t remember mine, but one I specifically remember my younger brother using was “nuk” for milk. The nipples that were used on his bottles were Nuk brand, mom got in the habit of telling us to use the clean “nuks” when we got the bottles ready (there’s 8 years difference between me and younger brother, and I’m the youngest next to him)…little brother picked up on it and milk became nuk.