The problem with profanity isn't that people are saying the words where other people can hear. They're just words after all, and no matter their meaning, people are free to ignore them. The problem with profanity is that people turn it into such a big deal, in the process spreading the self-reinforcing belief that it's somehow harmful. This conditions people to be offended by it and spread this toxic conditioning to others.

While they probably don't have very noble intentions, I personally feel that those teens you speak of are nonetheless actually doing more good than harm. The more people are exposed to profanity, the less likely they are to be offended by it, and the more likely they are to see it as a normal, acceptable thing. To someone like you who *is* offended by it, this probably sounds like a bad thing, probably exactly what you want to avoid. But I see it as desensitization, not corruption.

If everyone stopped caring what language their kids were exposed to, our next generation will likely grow up to be mostly if not entirely unfazed by profanity. And think about it critically: would this really be such a bad thing? Without the meaning people give to it, shouted profanities are nothing more than sound waves. If a person's first reaction to hearing this meaning is to laugh it off—perhaps judging the person negatively for it if it's something like the N word* being used in a racist way—without actually taking it as personally offensive, then more power to them, right?

If I were you, I'd give serious consideration to continuing to take my children to the park in spite of the bad language they'll inevitably hear. Your children are not going to turn into misogynists or racists or anything for it. You might want to have a talk with them about those words though, to explain how saying those words often hurts people's feelings, without actually conditioning your children to have this phobia themselves.

* No, I'm not a hypocrite for not saying the actual word here—though I do think you ought to desensitize yourself to it, I don't want to be rude. Also I'm not sure what this website's policy on it is.