This is completely inappropriate behavior. There should be clear boundaries between a mother and a son. Discussing sexual stories is not suitable in a parent - child relationship. It violates the norms of healthy family relationships and can cause great harm to the son's psychological and emotional development.
This is an extremely awkward and inappropriate situation. It goes against the norms of a healthy family relationship. You need to communicate your discomfort clearly. You can say 'Mom, this is not a topic that is suitable for discussion between us. Our conversations should be positive and appropriate. I hope this never comes up again.' If possible, try to distance yourself from such inappropriate conversations in the future and focus on building a more appropriate and healthy relationship.
We should avoid such inappropriate topics. Instead, we could focus on positive family stories like 'times when mom showed great kindness' or 'instances of mom's selfless love'.
Definitely not appropriate. A mother - son relationship is a very special and pure bond. Conversations should revolve around love, care, values, and normal life experiences. A sex story is a very private and adult - oriented topic that has no place in this family relationship. It can make both the mother and the son feel extremely uncomfortable and can also damage the healthy family dynamic.