I'd like to add that his behavior might be completely age-appropriate (you didn't go into details).
Say things to him to give him something to live up to, if you don't do this already. Something like, "You're such a nice kid, I want everyone to know the real you," or "I'm so surprised to see you doing/saying that," or "I'm sure you didn't realize it, but that hurt my feelings." Or whatever, start with the positive.
Don't say, "What's wrong with you?" I've done that a few times and it doesn't help things at all!
And, good luck!
Say things to him to give him something to live up to, if you don't do this already. Something like, "You're such a nice kid, I want everyone to know the real you," or "I'm so surprised to see you doing/saying that," or "I'm sure you didn't realize it, but that hurt my feelings." Or whatever, start with the positive.
Don't say, "What's wrong with you?" I've done that a few times and it doesn't help things at all!
And, good luck!