My nephew (when he was about three or four) saw a very large gentleman on the telly, pointed and said, "Look, that man's got a baby in his tummy, no, he must have a hundred babies in his tummy!" Sister and I looked at each other, smiled and replied, "Well, um, you know, men don't have babies." "Oh yes they do"! he insisted. We thought we'd better leave it at that rather than go in to more detail. He's 40 now and I think he has a better grasp of the facts of life these days.
We have two of our granddaughters here for a couple of days.
8 year old: what time is it? Me: about half past ten 8 year old: is that all? We've been up ages. Me: you flipping have!! 6 year old: Granny (my opposite number) says you shouldn't say flipping......its the f word!