I don't have kids, so this is a story told about my oldest nephew. He was the child who'd come in after playing and ask his mother, "Mom, what does @#$%&*@#$% #@$%#@@# mean?" Sis said he asked matter-of-factly, and she realized that he was just curious as to the meaning. She said she gave him an abridged definition, then asked calmly, "Where did you hear that?" From one of his friends. Nephew and friend were around 7 at the time.
A later one that I was an eyewitness to: Same nephew as above. He walked into their home with a friend, and they were apparently talking about what they wanted to do when they grew up. Nephew said, "When I get really, really old like my dad - you know, 29 - I want to build things." I looked over at BIL, who had the newspaper in front of his face, but the newspaper was shaking. He was laughing his head off back there. The kids went back outside, and we all laughed our heads off.
Different nephew, brother to the nephew mentioned above: I was talking to Sis on the phone, when I heard, "I want some bologna!" in the background. This was repeated several times, until Sis said, "Just a minute," to me and said to her son, "I have already told you twice and your father has told you once - we don't have any bologna! Now go away!" It was a few minutes before Aunt Sirius stopped laughing.
Both of the above nephews are now adults. The bologna-nagger is a teacher, and he told me back when he was in college that he had had too much to drink one night, but his mother made him get up and go to school. It was in the middle of summer in Texas, so we're talking hot weather, plus the air conditioning in the building where his classes were had broken down. Then there was a bomb threat at the same time as a power failure, and he had to traipse down six flights of stairs with a raging hangover in the heat. He told me, "I was sick as a dog, but I learned my lesson. I haven't had a drink since then."