I'm not aware of any specific "huge cock in tiny mouth stories" in mainstream literature. Most literature focuses on more positive, moral, and diverse themes.
If she means stories about roosters, you could simply start telling her about the time you saw a really colorful rooster at a fair. Just keep it light and fun.
This phrase is quite ambiguous. It might be misinterpreted as something improper. But if we consider 'cock' in the sense of a male chicken, it could mean she has an interest in stories about them. Maybe she grew up on a farm or just has a strange fascination with chicken - related tales. For example, stories about a rooster that wakes up the whole village every morning could be what she's interested in.
He could start by simply asking her what kind of stories she was interested in. For example, if she was interested in his childhood stories, he could begin with a memorable event from his early years.
He can simply ask her politely if he can see the stories she has created or shared. For example, he could say, 'Dear, I'm really interested in your stories. Can I have a look?'
If they share a device, he can wait for her to offer to show them. Maybe she'll be excited to share the stories she has. It's important to respect her privacy though, in case she doesn't want to share right away.
The phrase 'wants sons cock story' is really ambiguous. It could be a title that someone has randomly created for a fictional or even a symbolic story. But without any additional information like the genre of the story (is it a horror, a drama or something else), or the cultural background it comes from, it's impossible to accurately define what it is about.