This reminds me of the riddle where the answer is a watermelon....
"okay so there is this green house, and inside the green house is a white door(or house), and inside the white door is a red room(or house), and inside the red room there are black babies, what is this house?"
"okay so there is this green house, and inside the green house is a white door(or house), and inside the white door is a red room(or house), and inside the red room there are black babies, what is this house?"
something along those lines