We are learning opposites here. Up, down; front, back, etc. 
3 1/2 year old son: "Look Mama. I have a little hand, you have a big hand."
I said, "Yes. And see my foot is bigger than your foot, but someday your foot will be bigger than mine." 
Son: "And I have a cute little butt and you have a great, BIGGGGGG butt!" 
My answer: "Gee, nothing gets by you does it?"