5 year old son bad friends?

I have had the exact same issues with all of my kids, it seems like I am much stricter with words that are not okay than other parents. This is their choice, and I can't berate them for that. I used to keep my kids away from places and people I thought were bad and I finally learned that they are every where and will be for the rest of their lives. I told them that just because other kids do certain things (and I used very specific examples) that it does not make it okay for them to act that way. I told them that there will always be people who try to get them to do bad things or will act in a way we don't agree with and they have to say no, and act correctly. I don't know if you are religious, but I tell my kids that God is always watching, and I may not know if they misbehave but he certainly will. If you sons says those words, give him a warning and then sit him in a time out. Often we tend to not punish our children if they are being influenced by others, but again, this is part of life. Perhaps the other mother will sort it out. You can't keep him from living life, he just has to learn the hard way to stand apart and act as you would like him to, and he will proabably get in trouble along the way.