You can be around your mom most of the time when she is with people who might know the spanking stories. That way, you can quickly intercept any conversation that might lead to those stories being told. Also, if there are certain events or gatherings where this could be a risk, you could give a general warning to everyone there in a light - hearted way, like 'Let's keep all the embarrassing stories to ourselves today, especially around mom.'
You could create a bit of a mystery around it. Let people know that there are some personal things that you prefer to keep private between you and your mom. This might make people more curious, but also more cautious about not revealing anything that could be related to the spanking stories. You can also keep an eye on any signs that someone might be about to tell your mom something inappropriate, like a change in their tone or body language, and step in immediately.
Have a serious conversation with your friends. Just be upfront and say, 'Guys, spanking stories are off - limits when it comes to my mom. It's a family thing and I don't want her to know about it.' Most friends will respect that if you're clear about it.
You could share with them some of the negative consequences that might happen if your parents find out, like getting in trouble or feeling ashamed. This can make them more likely to respect your request.
If it's a situation where you can't directly stop the person, like in a group setting, you can try to create a diversion. Maybe spill a little bit of water accidentally (not too much to cause a mess) and while everyone is distracted by that, try to steer the conversation in a different direction.
You could directly tell that person that it's a private matter and you don't want your mom to know about it. Be firm and serious.
Set a time limit for yourself when talking. For example, decide that you'll only talk for 5 minutes at a time. This can help you be more aware of how long you're going on.
You can explain to your mom that spanking stories might seem strange but they could be related to various things. For instance, they could be about historical parenting methods or part of a story's plot to show a strict upbringing. Share with her that you were just curious about different ways of raising children in different times or places.
Well, it might make her uncomfortable. Spanking is a rather sensitive topic and she might not want to hear about it. Also, she could get worried or think that there's something inappropriate going on.
Limit your interactions to family settings. When you are around your sister - in - law, act in a way that is clearly appropriate. For example, don't touch her in any way that could seem improper. Also, communicate to your partner that you understand the importance of boundaries in this relationship.
You could directly tell that person how important it is to you that they keep it a secret. Be firm and serious about it.
Just be honest and face her. Apologize sincerely. She may be angry or shocked at first, but your honesty will help in the long run.