Green’s Dictionary of Slang

a popular drinking toast.

1960		H. Selby Jr ‘Tralala’ in Provincetown Rev. 3 82: Tralala lifted her drink and said chuckalug and banged her glass on the bar.
1964		H. Selby Jr Last Exit to Brooklyn (1966) 80: Tralala lifted her drink and said chugalug and banged her glass on the bar.
1969		A. Buzo Rooted I i: bentley: Chug-a-lug. gary: Chug-a-lug.
1986		H. Selby Jr Song of the Silent Snow (1988) 74: Come on Harry, chugalug.