Anonymous wrote:OP, I told my son, "Yes it is your right to say whatever you want. But I am sad and ashamed to hear a child of mine saying these things."
He said it was just a joke, and I said "yeah, I understand that it is just a joke, but I don't like that you are saying it, and I don't want to hear a child of mine saying things like this, not in my house and not in front of me. I can't control what you say to your friends, but I don't think it is right to say these things even as a joke."
Fair enough. But you might want to consider making it it less about YOU and more about HIM.
Teenagers are all about finding themselves -- their identity and their voice -- and alienating and pressing their parents' buttons is often part of it.
Another approach:
"Wow. That's seriously inappropriate. You know you're better than that, right? You have good judgment and you're not a jerk. Please stop acting like one."
If you find it continues, I would revoke privileges. Regularly and consistently. If it's repeating something on YouTube, he loses YouTube access for a certain amount of time. If it's something he heard at school, he loses access to the phone to text his friends after school for a set number of days etc.
But mostly I'd look him in the eye and remind him he's not that kid and never has been. He's a good person with good judgment. This is not who he is, and he needs to stop.