There are some reproductive expressions that I find adorable and age appropriate for young kids.
My younger brother was born when I was 3. I was jealous and I wanted to send him back wherever he came from.
After asking the same question about twenty times, I was told about a "special Mommy and Daddy hug" that put a baby in Mommy's tummy, where it grew for nine months.
an embrace (of sorts) that led to every human, which only adults or spouses should share.