A little 4 letter word

Our home has a little four letter word floating around. When it is said it is followed by squeals of joy and laughter. No matter what the punishment for saying it our boys cannot seem to keep it inside their little mouths. One of their favorite places to use this word is in the car when they have a captive audience. Spelling this word repeatedly will bring instant craziness to any 2 year old boys countenance. They feed off each other and I fear it will never go away. So what is this four letter word that comes with wild eyes of excitement whenever it is uttered...POOP! Yes, they are even saying it right now as they dance around me at the computer, aaaahhhh. Taatjes does not know how to spell any word except p-o-o-p. Trey was so proud of himself when he taught his brother how to spell this fun little word. "Mommy aren't I being a responsible big brother and teaching Taatjes how to spell." Yes and No. I know this is only the beginning of such battles to teach them that this is not a kind word when directed at someone or shouted for the fun of it. I fear what kind of words will be coming out of Teagues mouth when he starts to talk:( This is what stay at home parents are referring to when they say they have no adult conversation.