Phrase used as an ultimatum to tell someone that they must improve their performance, behavior or attitude or they will have to leave

You've been working here for five days and you've been late five days. Shape out or ship out!

Cinque giorni di lavoro e cinque giorni in ritardo. O ti metti in riga o te ne vai!

Your crazy lifestyle has gone on for too long. You are not a kid anymore, your future is at stake, so it's time you shape up or ship out

Il tuo sconsiderato stile di vita è durato fin troppo. Non sei più un ragazzino, devi pensare al tuo futuro, perciò o ti metti in riga o te ne vai

Mr. Brown was called on the carpet by the boss who told him: "I know that your office made a lot of big mistakes lately, so you'd better shape up or ship out!"

Il sig. Rossi è stato richiamato dal direttore che gli ha detto: "So che il suo ufficio ha commesso una serie di gravi errori recentemente, perciò si metta in riga o se ne vada"

The phrase originated in the U.S. Navy during World War II (1940s) as a threat against any sailor who wouldn't meet the Navy's behavior standards, meaning: "you behave, or you'll be shipped overseas to a combat zone". After the war, this idiom entered civilian life and started to be used in situations calling for improved performance