Apple = Nice "pee pee"?

Renee used to eat apples in small slices with its skin intact but later took a change from that to eating them in cube size without the skin. Recently, she took some of daddy's apples(sliced, with skin) and assuming that she likes it this way again, I prepared them the same way for her(after her lunch) a few days ago. However, after a few bites, she started to spit out the skin and told me she doesn't like the skin. *???*
I teased her : "U must eat the skin, it's good for you"
Renee : "No, I don't like"
I continued teasing her : "If you eat the apple skin, it'll make you mei mei ar, and your 'pee pee'(buttocks) will be nice nice ar"
Renee : (twisting/turning around to look at her buttocks) : "so cute"
hahahahaha