Boys

So, my kid is going through this very weird stage. Everthing he says is for shock value. He's testing us with words. Like the other day one of my really good friends came over and showed Calvin this weird finger thing. Calvin says, is that supposed to be a penis? He then just walked off. It's definately a 2nd grade boy thing. I'm around these kids enough to know it's what they do and talk about. I don't know if I should laugh, get upset, send him to his room, etc. I have been explaining to him that this is very inappropriate and I don't like it. That seems to be doing the trick but I'm getting to that point where I'm never quite sure what is going to come out of his mouth. Rrrrrr....