Men and Potty Humor

Why is it that men are fascinated with any conversation having to do with the bathroom, bathroom words, bathroom noises and bathroom items? I am repeatedly surprised when my husband and another man (brother, brother-in-law, close friend, etc) start a conversation completely unrelated to the bathroom and somehow always end up talking about bathroom stuff!

Today David made a point of showing Gary a segment on Andrew's video (Elmo's Potty Time) where Elmo, Baby Bear, Baby Bear's little sister and a Sesame Street Human talk about the various names for #1 and #2.... I must then tell you, although it should come as no surprise, that Andrew, David and Gary all erupted into many tones of laughter that can be described as none other than "male bonding." As child after child shouts their respective 'names' for #1 and #2, the laughter gets louder and louder. Then, to allow themselves to hear this banter continue, they raise the volume on the TV because they are all three laughing so loud, and Andrew shouts "Poo Poo!" ****This is where I interject that silly as this may be, I am definitely a mom, because there is some special proud feeling that I get when Andrew says this new word, but I'm sure it's novelty will wear off- I hope****

And amongst two other guy friends of Dave's, he managed to get the conversation to go there again tonight, and they all laughed and thought it was great! Potty humor this, few seconds of men grunting and laughing, a little knee slapping, more potty humor, and the cycle continues... what is it that is SO appealing about this subject for guys? It does not irritate me, but it sure baffles me each time it happens, and I don't know why I act surprised. I should know it's coming, I should almost be able to anticipate it by now....