In a game or sport- any physical space above, below or level with the playing surface that does not "count," i.e, the game, contest, etc. cannot be played on that surface and any object or player in that area is considered "out of play" and not eligible for the game that is occuring. Usually marked by lines, fences, flags, etc.

Also, An expression- meaning not appropriate, not polite for conversation.

Also, how to describe some part of a person's anatomy you cannot touch. Don't go there.