three strikes and you're out
three strikes and (one's) out
Three mistakes, transgressions, or infractions will lead someone to failing or being dismissed. He's got two strikes against him for coming into work late; three strikes and he's out. The school takes truancy very seriously: three strikes and you're out.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
three strikes and you're outINFORMAL
If a country or an organization has a three strikes and you're out policy or law, people who commit three offences are punished very severely, even if the separate offences are not very serious. Note: In baseball, a `strike' is a legal pitch or ball which the batter fails to hit. The batter is out after three strikes. California has recently introduced a law known as three strikes and you're out, meaning that after a third conviction the authorities lock you up and throw away the key. A Merseyside burglar has become one of the first in the country to be jailed under the new `three strikes and you're out' law.
Collins COBUILD Idioms Dictionary, 3rd ed. © HarperCollins Publishers 2012