I know what you mean, but I think cursing tends to become a habit over time. My family were not cursers, so I particularly find it offensive and unnecessary. But it seems to be more and more accepted.

If you have tried to ask them to tone it down and they don't, then I don't think there's a lot to be done about it except maybe to leave when they get going with it. But I don't know if that would help. After all, they are grown people.