If it continues, you may need to distance yourself from the person who is telling such a story. Because being around someone who likes to spread such inappropriate content is not good for your mental state. Also, in a more serious situation, if it violates any social ethics or rules, appropriate reports can be made.
First, firmly express that this is an unacceptable topic. For example, say 'This is inappropriate and we should not talk about it.'
This kind of topic involves disrespect and unhygienic elements, so I can't provide relevant stories.
There is no such appropriate story about a mother doing that on purpose. We should promote positive family values and behaviors in our discussions.
If you hear such inappropriate stories, you should firmly and immediately distance yourself from the person sharing it. Let them know that such topics are unacceptable.
Secondly, pile on the humor through situations. Make things go wrong in the most hilarious ways. Maybe a wizard tries to cast a spell to make it rain gold, but instead it rains fish that can talk and demand to be put back in the ocean. Also, use lots of exaggeration. If a character is running away from something, say they run so fast that they leave a trail of fire behind them just from the friction of their shoes on the ground.
First, it's important to have an open and honest conversation with your wife. Let her know how her behavior makes you and potentially others feel. For example, you could say 'Honey, when you tease my friend like that, it makes me uncomfortable and might also make my friend feel awkward.' Set clear boundaries about what is acceptable behavior in your relationship and in social interactions.
We should firmly oppose it and tell the person spreading the story that it is not acceptable behavior.
If you hear someone say this, you should firmly correct them. No one should tolerate such disrespect towards a partner. You could say something like 'That's a very unkind and inappropriate thing to say about your wife.'
One possible reason could be as a form of rebellion. In some fictional stories, a boy might do it to defy authority or social norms. For example, if he's angry at his parents or a strict teacher, he might use this extreme act as a way to show his dissatisfaction.
One should firmly and politely set boundaries. Let her know that her behavior is inappropriate and that you are not interested in engaging in any improper behavior. For example, you could say something like 'I respect your marriage and our neighbors' relationship, so this is not appropriate.'
First, try to stay calm. It's a natural part of growing up. Then, find a private place as soon as possible to clean up. Don't overthink it too much because it's a normal physiological reaction. And remember, it's a very private experience that most people won't know about unless you tell them.