たが最後・たら最後
ta ga saigo / tara saigo
once... (there's no going back)
[Once... (there's no going back)]
Connection: Verb (た-form) + が最後 / Verb (たら-form) + 最後
Usage: Expresses that once a certain action is taken, an irreversible (usually negative) consequence follows. "Once you do X, it's all over / there's no turning back." Carries a strong warning tone.
Examples:
あの人に秘密を話したが最後、全員に知られてしまう。(Once you tell that person a secret, everyone will find out.)
このゲームを始めたら最後、やめられなくなる。(Once you start this game, you won't be able to stop.)
一度サボったが最後、癖になってしまう。(Once you slack off, it becomes a habit.)