M.K.
It would cause a problem if you told them you didn't want your son around their's, that should almost be guaranteed. Can you arrange playdates to be at your house where you can monitor what is being done and said and encourage the other boy to follow your rules while in your home? I have done this in the past. My boys had friends who were rougher talking, I would have the boys to my home, correct them if they used language or behaviors I disagreed with, plied them with home made goodies, and modeled interaction. I don't know if any of it stuck for them, but I was able to have more control over the situation. If your friends won't moderate, then it's up to you and your son is your responsibility. If the friendship has to go, it just does. As a side note, he's about to start school and you CANNOT monitor that, so continue instilling your values in him at home and talk to him about what he sees. My kids know how they are allowed to act at home, what is okay. They don't act too differently with their friends that I can tell, from what I get from our conversations. I know my 14 year old swears around his friends sometimes. I told him that he's never to swear at home or in adult presence and that I would hope he keeps in mind he can be a positive force for other kids if he follows his own line and beliefs.