So, dd was throwing books down the stairs. As far as she was concerned it was a fabulous new game she'd invented and she was enjoying herself immensely. Cue stern mummy voice and removal of books whilst explaining that we did not throw books down the stairs in this house.
She raced off to the bookshelf to find some more books to chuck, squeaking with giggly excitement.
It was only as I was explaining that mummy was not laughing, it was not funny and throwing books down the stairs when mummy had said "no" was 'naughty' that I realised what naughty meant to her:
Naughty in all her books and songs is associated with a cheeky little monkey (usually) who's being 'naughty' but it's all funny and everyone is enjoying the joke. To her, naughty is not a negative thing, more impish and funny.
I can't decide whether to abandon the concept or find a new word!