Keep-away is a children's game. Two people throw a ball to each other, and one or more players in the middle try to catch it. If you catch it, you usually swap places with the person who threw badly, or you join the throwers — rules change from playground to playground. In the United States people also call this monkey in the middle; in Britain a close cousin is piggy in the middle. It is informal playground talk, not classroom English. The game is teasing by design: the people with the ball keep it just out of reach, and that is the whole joke. Grown-ups sometimes use keep-away loosely for any situation where someone is holding something back on purpose, but the named game is the children's one with a ball.