I was a kid.
Once upon a time, a long time ago, granted, but on this planet (let alone in this galaxy) nevertheless … so, I think I’m reasonably qualified to comment.
And I have to break it to people that … if my experience of both myself and other kids is anything to go by … the chances are that your eight-year-old uses language like this every fucking day
There’s also a not altogether insignificant chance that they tell sexually explicit jokes as well — long before the Internet (let alone the Web) was the germ of an idea, I knew loads of eight-year-olds who had been exposed to hard-core pornography by the time they were eight, because their elder brothers had magazines stashed under their mattresses.
Kids aren’t as innocent as people like to tell themselves — they just pretend they are when you’re around.