*time off for good behavior
1. Lit. a reduction in one's prison sentence because of good behavior. (*Typically: get ~; have ~; give someone ~.) Bob will get out of jail tomorrow rather than next week. He got time off for good behavior.
2. Fig. a shortened time period—such a meeting, period of punishment, school class, etc. (Jocular. *Typically: get ~; have ~; give someone ~.) They let me out of the meeting early. They said I got time off for good behavior.