I'm not sure what specific stories your mom loves without more context. It could be mystery novels, love stories, or adventure tales. Maybe she likes stories about family and relationships.
It's not a suitable or common topic to discuss. Moms deserve respect and positive portrayals, not something like this that might be seen as odd or inappropriate.
You can respond in a positive and respectful way. For example, you can show that you appreciate her attraction but also remind her that there are other aspects of you and the relationship that are important.
You could look for adventure stories with heroic characters. They often have elements of grandeur and excitement that might appeal to her love for 'big' things in a more appropriate way.
This is extremely inappropriate behavior. Mother - child relationships are based on love, respect, and propriety. This kind of behavior violates basic family values and human decency. There should be no such stories as it is a form of psychological and moral aberration.
First of all, such 'cock stories' might be inappropriate or not something that is commonly shared in a family context. Maybe your mom is just shocked or doesn't know how to respond. You should stop sharing such stories. Try to engage in more positive and family - friendly conversations like talking about your school, hobbies or future plans.
Yes, it is clearly an inappropriate interest. Such a topic is private and should not be a subject of interest among people in this relationship. It violates the normal boundaries of friendship and marriage.
One way is to use examples from her own experiences. For example, if she once had a situation where she wasn't listened to, remind her of how that made her feel. Then, relate it to how you feel when she doesn't listen to you.