In order to discourage early game disconnects that can negatively affect the gameplay experience for other players, Call of Duty: Black Ops II has implemented a probation system that will penalize players that frequently leave games early. The probation will not allow the player to connect to multiplayer matches for a limited time. If continually abused, the time the player is on probation will increase.
In order to avoid receiving the probation penalty, you must remain in a match for its entire duration.