When I was little (and being a city boy), I thought kindling wood was ‘kinlin wood’. I also couldn’t figure out if the little stream by my grandparents’ place in the woods was a ‘crick’ or a ‘creek’.
In High School, one of the guys in my World Culture class wrote down that the Israeli Prime Minister was Gold In My Ear.
These are coming back to me as I read others’ responses:
The popular beach/net/ball game: “Bally ball”
What my imaginary Indians shot cowboys with: “Bone arrow”
And to the republic
For Richard Sands
One nation, under God…
Around the same age, I was puzzled by my parents’ shocked reaction when I quoted these lines from MAD Magazine:
…because I had looked up “vibrator,” and the dictionary said it was a device for giving massages.
Let me guess. You not only live in Maryland now, but grew up there too?
Same here. In fact I don’t think I knew about the other version until well after I’d graduated from college.
When I was about six, I saw a dime drop on the floor and tried to return it to the man I thought dropped it. He said it wasn’t his and let me keep it, saying, “I guess you’re a dime richer.” I interpreted “dime richer” as meaning someone who got rich by dimes. I thought that was a ridiculous assumption for him to make, especially since it was the first time I had ever found a dime. I also thought it was weird of him to use “rich” as a verb. It was probably twenty years before I replayed the incident in my head and it suddenly made sense.
When I was a child, our teacher cited ten commandments in King James version. So I thought that the word “thou” is same as though.
When I was a tyke, there were a lot of PSAs about TB. I thought they were saying “TV”, and wondered why they were warning us about TV on TV.
A classmate wrote about “a mean ole acid”.
My son thought “adult supervision” meant that his parents could see thru walls.
My mom warned me about a boy who got his penis caught in his zipper and they had to cut it off. It was years before it dawned on me that the “it” was the zipper not the penis.
I was 5 and had broken my left arm by falling off a sidewalk-size bicycle when riding it double on the handlebars.
A friend my own age and I were walking by a Dairy Queen, my arm in a cast and sling, when a man about to buy something at the walk-up window looked down at me and asked, “Are you broke?”
I thought it a funny way to ask if my arm was broken. Of course it was. Maybe he’s blind, but if he’s blind, how would he know my arm is broken? I gave up and said, “Yes.”
So he bought me an ice-cream cone and my friend got nothing.
I thought “eavesdropping” was “eavestroughing” and pictured someone hanging outside windows from the eavestrough listening to conversations.
Yikes. You poor kid.
Through first grade, I thought the Pledge of Allegiance was referring to “widget stands,” though I wasn’t sure what a widget was, or what you’d stand it on.
(“And to the republic for widget stands…”)
Until I was well into my twenties, I thought that when someone smoked a bowl, the bowl was like the size of a salad bowl or soup bowl.
'Stick, ‘em’ for setting a dog on someone instead of 'sic ‘em’ (I still think 'Stick ‘em’ makes more sense).
Something that lasted well into college, ‘cheat-cheat’ instead of ‘cheat sheet’ for the small notes one carried into tests at school.
I am pretty literal-minded so I thought searching an area with a fine-tooth comb literally meant combing through dust and dirt. With one of those black plastic combs. 
When I was in second grade, I accidentally popped another kid in the eye while playing during recess, and was awarded a revoked recess period, to be spent, instead, in the “All Purpose Room”. I distinctly recall preparing a speech to the Nun Of Punishment that I believed the room should be called the All Accident Room.
When I was about 5 years old, my older brothers took me out to a nearby woodsy area they liked to explore. I fell down on some gravel and got a nasty scrape on my knee. On the way home, presumably to make me feel better, they said, “You’ll get the Purple Heart for this,” and I freaked out, thinking that purple heart was some kind of horrifying blood disease.