Green’s Dictionary of Slang

(US prison) an escape.

1927		D. Hammett ‘$106,000 Blood Money’ Story Omnibus (1966) 327: Papadopoulos had arranged a crush-out for Flora.
1934		L. Berg Prison Nurse (1964) 99: From mouth to mouth it had spread ‘crush out!’ ‘Lucci got away’.
1943		R.L. Bellem ‘Dead Man’s Guilt’ Dan Turner – Hollywood Detective May 🌐 A three-time loser who’d got blasted to his ancestors up at San Quentin [...] while trying to pull a crush-out.
1953		T. Runyon In For Life 125: If a crush out was ever tried — if convicts ever seized him or another official and tried to use them as hostages while forcing their way out — they were to shoot.