Green’s Dictionary of Slang

1. a male, esp. a male friend.

1907		D. Runyon ‘The Defence of Strikerville’ in From First To Last (1954) 13: Here’s a gee hungerin’ to slip us two bucks a day.
1915		G. Bronson-Howard God’s Man 212: He knew that kind of gee always hollered for the law.
1928		R.J. Tasker Grimhaven 11: You ought to see what some of these gees are doing.
1934		L. Berg Prison Nurse (1964) 114: What the hell can a ‘gee’ do when he ain’t been stayed with in years?
1940		D. Maurer Big Con 148: You smart gees have lost more men than there are rabbits in [...] Michigan.
1959		Murtagh & Harris Who Live In Shadow (1960) 107: To hell with the righteous gees who make with the pretty talk.
1962		Ragen & Finston World’s Toughest Prison 800: gee – Any individual – ‘guy.’.

2. as the gee, the head gee, the whole gee, the most important person in a given environment; the leader.

1912		Bulletin (Sydney) 26 Dec. 15/1: Edith: ‘I ’erd yer got the bullet frum de jam fact’ry, Smacker.’ / Smacker: ‘Sure! De ’ead gee arst me if I’d go ter ’is funeral if ’e snuffed out; an’ I sed I’d be only too glad.’.
1921		P. & T. Casey Gay-cat 69: That’s the ranch of old Curt Haines who is the whole gee in these parts.
1964		H. Selby Jr Last Exit to Brooklyn 27: We was the gees on the first bench and what we said was law.
1997		100 Sneaky Little Sleuth Stories 31: Wonder who’s the head gee around this dump?