Barbie's butt and vulva

"What's wrong?" Special K asked worriedly as she showed me Barbie's butt. Barbie's butt is not flesh coloured. Instead it's grey with the letter B stamped all over. "Barbie's butt has the letter B stamped on it." I explained to her. "Where's her vulva?" she asked. I said "She doesn't have one." We both looked and there was no crease. "She has a butt crease, but not a vulva." I explained. She asked "Does Barbie wear big girl underpants?" I replied "I guess not." She immediately put Barbie aside and started to "read" a picture book.