If you're not familiar with the Young Nicholas stories, they're stories about Nicholas, a young school boy, and all the mischief he makes at home and school with his friends. They're really cute, and they've been translated into several languages.
The humour of the books derives from their unique story-telling style: the adventures of Little Nicolas are told in the first person by Nicolas himself. On the one hand, the books are a parody of the story-telling habits of little children; for example, the author makes frequent use of stylistic features such as run-on sentences and employs an egocentric, naive point of view. On the other hand, adults are the targets of the books' humour when the straightforward and uncomplicated worldview of the child narrator exposes the flaws of adult perception. The subversive element in the Petit Nicolas thus made it an early example of modern children's literature that is centred around the experience of the child, rather than an adult interpretation of the world.
I used a little collection of Petit Nicolas stories for a couple of my French conversation classes at BYU, so it was fun to learn more about the inspiration behind the books.