Green’s Dictionary of Slang

(US) a spittoon.

1922		T. Thursday ‘Ten Dollars – No Sense’ in Top-Notch 15 Dec. 🌐 The bird [...] paid less attention to the sawbuck than if it was an Ignited Cigar Store goopon.
1933		J.T. Farrell Gas-House McGinty 40: McGinty stumbled over an overturned goboon.
1949		N. Algren Man with the Golden Arm 44: There was [...] an old-fashioned golden goboon for every four bar stools.
1964		J. Thompson Pop. 1280 in Four Novels (1983) 378: Buck tossed his stogie in a gaboon.
1997		K. Jonas Dansing Star 🌐 Ch. iii: Beside the bench sat a gaboon, a spittoon made of a plug tobacco box filled with sand or sawdust.