I heard my little sister say “Oh sit!” once. Mom was in the next room but didn’t catch on. I pulled sis aside and straightened her out. (She got the word from another, older sister.)
My brother thought is was funny that when you throw a big rock in deep water, it goes “DOUCHE.” And it does… But he said it once too often around Mom and she told him to quit, so he started saying it even MORE often!

A few years ago I was supervising a test in a class. One of the kids pulled out her textbook in plain sight. I came and scolded her for cheating in class. She said “I’m not cheating, I’m just checking if my answer is right”.

She was only six or seven so I just chalked it up as her being clueless. Still quite funny though :)

She was about 5 and we went to the zoo. Two camels were mating. She said, “Those camels are mating!”

My sister, around 6, “Humans were created by apes.” A friend, “Yes, and first they made Adam and Eve.”

My cousin, 5, seeing me eat some black liquorice and then coughing: “I guess it wasn’t so smart to eat that cable or hairband after all.”

Same kid, seeing a dead pigeon, “Oh no. A broken owl.”

(Not my kid) On a visit to our house, my 7 y.o. nephew took out the trash with my husband. It had been raining and was really muddy. Upon entering the house afterward, my nephew began walking away into the main part of the house. My husband said, “Nephew, don’t you need to wipe your feet?” The nephew obligingly came back and vigorously wiped one foot on the mat, then began walking away again. My husband said, “Hey nephew, what about your other foot?” The nephew (a smarty pants who was always right) said, “It doesn’t get dirty.”

So many! I’ll go with the most recent.
Last Sunday my son and his family came out and we had a cookout.
His son, Cooper, just turned 6 last month.
We were sitting around the picnic table and out of the blue Coopy said “What’s it like getting old?....Psyche!!!! That was a Gramma joke!”

I took another grandson to a local park that has hundreds of ducks and geese. My grandson was about 8 at the time.
It was spring time and we came across dozens of nests.
Suddenly my grandson yelled “IT’S DUCK DATING SEASON!!!”

When my daughter was just learning to talk, she looked at me very happily and said “Fuck!”. I was stunned and asked her “what?” She said “Fuck!” again. I told her I didn’t understand so she showed me a picture of Kermit and said “Fuck!”. I told her it was pronounced FROG.

When my daughter was 3 I taught her how to write her name, CORY. She didn’t know how to read. She just knew these symbols had something to with her.
One day I walked into the living room and there was C O R Y in big letters on the wall in crayon.
“Cory! Come here!”
She came.
I said “We write on paper, not on walls!”
She looked in astonishment at her handiwork, then back at me, and said “How did ju know it wass me??”
Parenting is so hard some times!

Not my kid but the clerk at the convenience store told me this story about her son. He was about 9 at the time.
A guy with a dog moved in next door.
One day her son came running in almost in tears.
“He calls the dog the most horrible names! Why does he call him that??”
When Mom got the chance she approached her new neighbor and asked what his dog’s name was.
He said “Oh, his name is Baxter.”

Not funny, but charming: I do Halloween. I decorate, I dress up…the whole 9 yards. A couple years ago I had a girl and her younger sister show up for Halloween. They both greeted me with a somewhat hesitant “Trick or Treat”. I gave them candy and wished them a good night of treating. The girl paused and we had the following conversation:

Her: “I was nervous about coming here this year”.

Me: “Good”.

Her: “Were you the clown last year?”

Me: “I was”.

Her: “I was nervous about coming here last year too.”

Me: “Good. What can I do to make you nervous to come here next year?”

She proceeded to get excited and start telling me all sorts of things she wants to see. Apparently I have to do a Little Shop of Horrors theme next year.

When my other daughter was about 12 I had reason to say to her “People who live in glass houses shouldn’t throw stones.”
She looked at me oddly and said “They shouldn’t have sex either.” :D