Bodily Functions

What is it about bodily functions that little boys find so funny? Collin has been giggling at bodily functions for a while now but he's taken it to a new level recently. Someone taught him the word "burp" recently. Now he uses it even when he hasn't burped and giggles like its the funniest word in the whole world. I try to tell him if he's going to burp, even fake ones, he must learn to say excuse me afterwards. That's just as funny as burping in his eyes. Even funnier than burps? Farts. Oh yes, he learned to give arm farts a long time ago and I thought we were beyond that, however I was wrong. Its recently come back, and with a vengeance. Apparently when he was out to dinner with Aunt Bella and Max the other night he began making arm farts on Max's arm. Then tonight, again at the table (this time just for snack) Collin actually farts and says "Did you hear that?" I told him I did and he bursts out laughing and says "Collin poop again!" (he hasn't learned the difference between actually pooping and just farting) Why is this so funny? I have absolutely no idea, but he giggled and giggled like it was the funniest thing ever. I must admit, the part I found funny was when he asked if I had heard it. I giggled and giggled over that. I can't wait till he grows out of this stage. Unfortunately, most grown males I know still haven't completely outgrown this stage so I think we have a long way to go.