This classic riddle asks: what has a top and a bottom but no middle?
The common answer is a bikini.
A bikini is made of two separate pieces: a top and a bottom. Unlike a one-piece swimsuit, there is no fabric connecting them through the middle.
The clue sounds as though it might describe an object with a missing center, but the answer depends on the familiar names of the two parts of the swimsuit.
That is what makes the riddle work. “Top” and “bottom” are not being used as positions on one solid object. They are the names of two separate pieces, with the middle left uncovered.
