Expanding Vocabulary

So my 3 year old son said his first cuss word today. I couldn't believe it! He was talking about his friends at school and that some of them say "cry baby". Then he said "J" (protecting the identity of his friend!) says "B****"! What?! Then he says that "J" also says "You can't shoot" (the basketball). I don't think I like this "J" kid very much! Miles said B again and I calmly told him that wasn't a nice word at all and we didn't say that. I tried not to make a big deal about it because it seems that sometimes when you make a big deal about something, it makes him want to do/say it even more. I hope he doesn't repeat this anymore! And I'll be talking with the teacher in the morning...