Green’s Dictionary of Slang

very drunk; thus swack v., to get drunk.

1926		S. Young Encaustics 4: To swack was to get drunk.
1930		D. Hammett ‘The First Thin Man’ in Nightmare Town (2001) 391: I can always tell when I’m getting swacked because the skin gets tight across my forehead.
1938		J. Archibald ‘Bird Cagey’ in Popular Detective Jan. 🌐 He was swacked and he handed me his card—or that was what he thought.
1945		R.L. Bellem ‘Coffin for a Coward’ in Hollywood Detective Dec. 🌐 Bonham wasn’t a tippler, ordinarily. Then why had he got swacked to the scalp this evening?
1959		S. Bellow Henderson The Rain King 12: Damn these weak drunks! [...] I can’t stand these clowns who go out in public as soon as they get swacked to show how broken-hearted they are.
1969		‘Iceberg Slim’ Mama Black Widow 18: There was Lovell half swacked.
1979		E. Torres After Hours 126: He was swacked out of his skull.
1981		J. Wambaugh Glitter Dome (1982) 222: He can see the dude’s swacked.
1984		I. Doig Eng. Creek 75: I had seen my share of swacked-up people.
1990		(con. early 1950s) J. Ellroy L.A. Confidential 250: Joanie Morrow – swacked on champagne punch.
1997		E. Mordden How Long Has This Been Going On 178: Tom has gotten into his parents’ liquor locker and he’s getting — as his coevals like to put it — ‘swacked’.