OLD joke. The wedding ceremony was coming to and end and had reached the point where the groom kissed the bride. In the hushed silence a child’s voice rang out: “MOMMY, IS HE SPREADING THE POLLEN ON HER NOW?”
When my daughter was little, maybe 3 or 4, her gerbils had babies. She started crying and I asked her why. She sobbed, “I can’t believe I missed the wedding.”
When I was about 4, we went to “visit” my grandfather in the cemetery. When my grandmother was taking us to the grave, she pointed and said “he’s over there” and I saw some (random) guy in a suit in that general direction. I got the impression that you could still visit and talk to dead people, but only in the cemetery. I thought we were going to talk to grandpa’s ghost. A bit of a letdown to just stare at a stone marker with letters and numbers on it.
When I was that age, my family had a pair of cairn terriers. At some point, I also thought of them as “husband and wife”.
I have a cousin (once removed) in her 60s, who still thinks this. She thinks the male dog impregnates the female cat, which gives birth to a litter of mixed puppies and kittens.
She also thinks Alaska and Hawaii are right off the coast of California, like in her grade-school maps.
At that age my daughter had a corn snake that ate mice. We had a mouse breeding operation going and she loved it.
She knew that the girl mice had the babies. One day I realized there hadn’t been any litters born recently, so I examined the six adult mice and saw they were all females.
When I told my daughter all her mice were girls, she was thrilled since that meant more babies. That led to a discussion on why boy mice were necessary.
In second grade? It’s things like this that remind me that we all have such different upbringings. I was barely 6 when I saw my brother’s birth in person, and had known for at least a year already at that point how babies were made.
I was an only child, so there were no younger sibling experiences for me. And my mother was woefully unaware until she was an actual adult how sex worked and was loath to talk to me about it at all. We got ‘the talk’ in school when I was in 6th grade, which confirmed much of what we were hearing on the playground by that time. 
I grew up in the '70s, and we had “the talk” in school in 5th grade (so, I would have been 10 or 11). By that point, I suspect that the savvier kids in my class already knew about sex (either from their parents, or from other kids), but I was really naive about some things, so it was the first I learned of it.
I had figured out that babies were formed inside their mothers’ bodies, rather than bought at “the baby store” by the time I was 5 or so, but how they got there was unknown to me until that day in 5th grade.
I can’t remember how old I was when this happened, but one day I came upon my dad’s Playboy magazines and remember being completely confused about how a little girl’s body like mine got to looking like that as an adult. Of course I still didn’t end up looking like that, exactly, but puberty was not a concept that was in my head at all at that point!
I was so naive that when, during a parent-teacher conference, my teacher said we’ve been studying “human reproduction” I was really hoping that my parents didn’t know that meant SEX.
In retrospect, I think they knew.
What I find interesting, in retrospect, is that I first saw pictures of naked women when I was 9, in a Penthouse magazine (given to my cousin and me by a classmate, from his dad’s collection). Even though I didn’t know what sex was at that point, some bit of my brain did seem to understand that good-looking naked women were, well, attractive.
In my family, with 5 kids, my dad would grab one kid to help with a project or repair he was doing. So he asked me to hold the flashlight when I was probably 4 or so. I though for him to see the light where he was looking I had to shine it in his eyes. Then his illuminated eyes would magically see everything brighter.
StG
I believed as a kid that a form of mind-reading was real and that if you knew something, it really was possible for another trained person to “scan” your mind in some way and pull out your hidden thoughts. Something along the lines of the Vulcan mind-meld.
It’s part of what kept me good (paranoid might be a more accurate word) for so long… the thought that no matter how perfect I covered something bad up that someone with the right powers could basically find and read the universally recorded hidden camera footage that was constantly being recorded of everyone, every where. We weren’t religious but it would have been the equivalent of believing in an all-knowing God… or Santa Clause.
Except that instead of the power being held by one supernatural “thing”, it was a high-level skill taught only to certain senior-type master officials who used it for the most important things like national security and crime-fighting. But, if you were really bad, one of these telepathic ninjas might be sent out to you and like opening a filing cabinet they’d pull out and read all your secrets and you’d be punished for everything. So you’d better never do anything bad and leave a memory that could be read one day.
I first encountered the term “pet peeve” around age 7 while reading a kids’ magazine profile of some cartoon character, which said that his pet peeve was “dog drool.” So I spent the next few years thinking “pet peeve” meant “thing that annoys you about your pets.”
When I could just barely read, I was going through a men’s magazine, probably like Argosy, and there was an article entitled “DeGaulle’s Fabulous Bloopers”. I remember the name somehow, but I’m sure I didn’t read the story. Also in the mag, which interested me more, were some topless pictures. Somehow, in my fevered brain, I got the notion that breasts were called bloopers. It sounds right!
When I was like 5, I thought that rather than having different words for everything, other languages worked more like a cryptogram. The words were the same, but each letter was pronounced a different way than it was in English. Thus, if you could figure out what each letter was in that language, you could speak the language.
I think this mostly came from names like Johann and Jose, where the J is pronounced differently than it would be in English. So if J makes a Y sound in German and an H sound in Spanish, it made perfect sense to me that the same rules applied for the other letters. So if you knew to pronounce every J as a Y, you were 1/26th of the way to knowing German. And at that age, you’re absorbing all kinds of new language all the time, especially if you’re learning to read. So when you try to sound out a foreign word and someone tells you that the phonics rules are different in that word’s language of origin… well, it supports the theory.
Still, it was endlessly frustrating for me and probably for my parents as well when I would as them what “S” was in French or whatever and could not for the life of me make them understand what I meant and what I was asking, nor could I accept that what I was asking was nonsense.
The hero in “Jude the Obscure” (by Thomas Hardy) had that belief as well.
Ever since his first ecstasy or vision of Christminster and its possibilities, Jude had meditated much and curiously on the probable sort of process that was involved in turning the expressions of one language into those of another. He concluded that a grammar of the required tongue would contain, primarily, a rule, prescription, or clue of the nature of a secret cipher, which, once known, would enable him, by merely applying it, to change at will all words of his own speech into those of the foreign one. His childish idea was, in fact, a pushing to the extremity of mathematical precision what is everywhere known as Grimm’s Law—an aggrandizement of rough rules to ideal completeness. Thus he assumed that the words of the required language were always to be found somewhere latent in the words of the given language by those who had the art to uncover them, such art being furnished by the books aforesaid.
It didn’t end well for him (mainly because he’s in a Thomas Hardy novel, of course).
My music teacher in private christian grade school told us literally this. When I passed it along to my mom she was a bit upset about what she was getting for her money.
Woke up one winter morning and I was amazed by the frost on the windows. I asked my brother how it happened and he said Jack Frost did it, see he’s going to do more houses down the street and he pointed to a figure just visible in the snow with some sort of bag. Years late I realized he was pointing to the local newspaper boy.
When vacationing in California, I thought they had installed lights in the road. They were just reflectors.
My nephew on his first day of school introduced himself as Mikey No No.