one strike, (and) you're out

colloquial A policy in which someone will fail or be dismissed if they make a single mistake, transgression, or infraction. Based on the more common phrase "three strikes, (and) you're out," itself modeled on baseball terminology, in which a batter is "out" (no longer in play) if they miss the ball and earn a "strike" three times. The housing project has a very strict "one strike, you're out" policy due to the huge demand for apartments. I don't tolerate mistakes in my company, Thomas. One strike, and you're out.