It' a poopy day!

I am trying really hard, but I don't understand my children's fascination with bodily functions. I am constantly asking my 2 year old if she pooped, her reply, "no, just pee." My 4 1/2 year old finds it completely hilarious to say poop and pee about 200 times a day. Which in turn gets my 2 year old to repeat everything my 4 1/2 year old says.
The best is when my older is screaming, "MEGAN POOPED! CHANGE HER NOW! SHE STINKS!"  In my amusing mind, I say, "In a minute." "NO!! NOW! I CAN'T WATCH MY  CARTOON WITH THAT SMELL!!!!"  It really is bad considering she leaves a vapor trail of stink.  So, I get my little one in the bedroom, pull off her pants, and she says, "See, See? It's green!" That is her answer for every time she poops. Really, the only time that happened was when she had a cupcake with green frosting. It was pretty interesting to see this lime green poop. Hence, every time I change her poopy diaper she says, "GREEN!"  Than she grabs a wipe and tries to clean herself. I end of screaming "NO!" Now I have poop on my hand, on the bed, and on her socks.
I neve thought the last 5 years of my life would consist of telling one daughter to stop saying poop and the other to stop looking at her poop.