It's completely inappropriate. A mother should be a role model in propriety. Such stories are not only improper in terms of content but also may make the friend's son feel uncomfortable or even exposed to inappropriate information. It's much better to engage in conversations about things like sports achievements, cultural events, or recent interesting news.
The friend whose son was involved should have a calm conversation with the mother. Let her know that such topics are unacceptable. The mother should also take steps to educate herself about appropriate conversation topics with children. For example, she could read some books on child - friendly communication. And the mother needs to be more cautious about her language and topics when interacting with the son again.
Such a story is not suitable for proper discussion as it may contain offensive or inappropriate elements. We should focus on more positive and meaningful topics.
Mom could also keep a journal or a scrapbook about her son's growth. This way, she can document his achievements, challenges, and the lessons he learned along the way. It's a tangible way to watch his growth story unfold.