Green’s Dictionary of Slang

1. (US) an arm.

1909		Van Loan ‘The Cast-Off’ in Big League (2004) 52: What Jaggs referred to as ‘the old soup bone,’ the same being the salary arm.
1919		Van Loan ‘Piute vs. Piute’ in Score by Innings (2004) 314: Beemis is having trouble with the old super [...] His arm hurts him.
1919		T.A. Dorgan Outdoor Sports 7 May [synd. cartoon] I guess that was when your old souper was right. You were some hurler.
1919		Van Loan ‘The National Commission Decides’ in Score by Innings (2004) 297: Lefty’s arm is sore this spring, and any time the old soup-bone bothers him, he’s a crab for fair.
1939		Wodehouse Uncle Fred in the Springtime 169: ‘[O]verestimating the limberness of what is known in America, I believe, as the old soup-bone, he put his shoulder out’.
1978		Cincinnati Enquirer (OH) 20 Jan. 18/1: Which athlete earns his salary with his ‘soupbone’? [...] Pitcher.

2. the penis.

1992

(con. 1920–57) Randolph & Legman Ozark Folksongs and Folklore II 787: Of a man who is ‘well-hung’ it is said ‘he sure has got a fine soup-bone hanging on him.’.

3. (US) the tongue.

1935

J.T. Farrell ‘The Oratory Contest’ in Short Stories (1937) 156: Well, Gerry, how do you feel? The old soupbone in your throat loosened up?

4. (Aus.) a term of address to a thin person.

1991

R.G. Barrett Between the Devlin 16: ‘Please yourself, you miserable big prick.’ ‘Mr Miserable Big Prick to you, soupbones’.