Green’s Dictionary of Slang

to move straight towards, to approach directly; usu. as belly up to the bar, to begin a prolonged drinking session.

1907		S.E. White Arizona Nights 38: How’d you like to be doin’ a nice quiet job at gardenin’ in the East, where you could belly up to the bar reg’lar every evenin’.
1908		Sporting Times 11 July 1/4: He had a beautiful sosh on, but was bravely bellying up to the bar in a British Columbian town.
1909		R. Service ‘The Man from Eldorado’ in Ballads of a Cheechako 72: They signified their sympathy by crowding to the bar; / They bellied up three deep and drank his health.
1933		S. Walker Night Club Era 33: Twenty-four men could belly up to the bar without undue crowding.
1942		W. Pegler George Spelvin Chats 59: Americans eat hot dogs. At the races the aristocracy belly up to the counters and take them from the hands of the counter men.
1953		T. Runyon In For Life 131: The Warden invited me to belly up to a full-fledged bar.
1955		B. Schulberg On the Waterfront (1964) 7: After twenty years of bellying up to the bar.
1960		J.D. Macdonald Slam the Big Door (1961) 171: Let every man belly up to the bar and order his own poison.
1969		‘Iceberg Slim’ Pimp 29: Everybody belly up to the log and get twisted on me.
1979		G. Swarthout Skeletons 173: He’s probably bellied up to a bottle by now, the worthless bastard.
1985		N. Pileggi Wiseguy (2001) 98: Jimmy was the kind of guy who would belly up to the craps table and play until his ankles swole.
1990		J. Wambaugh Golden Orange (1991) 268: Buster bellied up and said, ‘Gimme a Wild Turkey, Spoon. And Polish vodka for Winnie’.
2001		‘Randy Everhard’ Tattoo of a Naked Lady 17: He bellied up to the counter and gave it a shot.
2011		J. Mabus ‘Sally Gal’ 🎵 Belly right up to the bar / And tell ’em ‘two cents plain’.