Something to flip can refer to two different objects: a LID and a COIN. A LID is a cover or top for a container, usually made of plastic or metal. It is often used to keep food or other items fresh. A COIN is a small, flat, round piece of metal that is used as money in many countries. Coins are typically made of copper, nickel, or other metals. Both lids and coins can be flipped, either to open or close a container, or to play a game.