It could mean that the girl wants the guy to really value and believe in the stories she tells. Maybe she shares her dreams, experiences or ideas through these stories, and hopes the guy will give them due attention and respect, like taking stock of something important.
There could be many interpretations of such a phrase. Maybe it's about some comical or absurd situations where things go wrong in a very extreme way. But again, without clear definition, it's just speculation.
No, it is not appropriate at all. Such content involves vulgar and inappropriate sexual implications which are not suitable for public discussion or sharing.
Perhaps in some extremely avant - garde or underground literature there could be something related, but this would be very hard to find as it goes against the norms of most literary works which tend to focus on more common themes like love, conflict, and self - discovery rather than such a strange and unorthodox concept.
In the vast collection of folk tales from different cultures around the world, we find stories about animals that can talk, magic spells, and brave heroes. But the idea of 'growing cock ass expansion' is so far removed from the normal themes of folk tales that it's safe to say there are no such stories within the realm of folk tales.
A young artist might have cocked up her first big art exhibition. Maybe some of her paintings didn't turn out as she hoped, they seemed 'hard' to look at in terms of the result she desired. But she took the criticism well and used it to improve. She experimented more and now her works are much better and well - received.