Green’s Dictionary of Slang

1. to down a drink.

1947		(con. 1942) J.H. Burns Gallery (1948) 184: I’m almost afraid to chugalug a drink or go out with a pretty little French girl.
1953		L. Uris Battle Cry (1964) 137: Burnside chuggalugged his third bottle down.
1957		‘Weldon Hill’ Onionhead (1958) 201: ‘[We] are goin’ to a sayloon an’ chugalug a couple of barrels of suds’.
1966		M. Rumaker Exit 3 and Other Stories 39: Jim chug-a-lugged, picked up his knapsack and followed the sailor out of the bar.
1976		N. Thornburg Cutter and Bone (2001) 74: He [...] came out with Mo’s bottle of Lavoris, which he proceeded to chugalug, gargling it and spitting it into a dead potted cactus.
1981		J. Ellroy Brown’s Requiem 65: He’d chug-a-lug a half pint of bourbon, get up on a card table and suck his own dick.
1981		L. Bangs in Psychotic Reactions (1988) 303: If you’re feeling uptight and truly would prefer to sail into the mystic, just chuglug two quarts of coffee and throw on side one of the first Clash album.
1996		J. Byrell Lairs, Urgers & Coat-Tuggers 134: Everyone - bar Big Oscar - laughed heartily, chugalugged their beers, slammed their glasses back down on the bar and waited for Big Oscar to get ’em in again.
1996		K. Lette Mad Cows 237: Ignoring the wineglass Gillian offered, she seized the bottle, chug-a-lugging.
2001		J. Stahl Plainclothes Naked (2002) 168: Tony hoisted the Colt .45 forty-ouncer [...] and chugalugged half the bottle.
2019		D. Jenkins Reunion 89: T.J. picked up the Dr. Pepper off Shoat’s desk and chug-a-lugged it down.

2. to get drunk; spec. to drink a whole bottle in a single gulp to attain drinkenness quickly.

1970		(con. 1950s) H. Junker ‘The Fifties’ in Eisen Age of Rock 2 (1970) 99: Chug-a-lug. Getting blotto, stinko, shit-faced.
1954		J. Sanders Freak Show 80: ‘[I]f you want to get drunk in a hurry, we’ll get drunk in a hurry. We can chug-a-lug’.