Green’s Dictionary of Slang

1. (US) bacon.

1863		T.F. Upson diary 4 Jan. in Winther With Sherman to the Sea (1958) 40: We need the ‘hard tack’ and ‘s.b.’ (sow belly) oh so much.
1865		T.F. Upson diary 11 Mar. in Winther With Sherman to the Sea (1958) 158: We have plenty of coffee and hard tack again and some S.B.
1915		H.E. Rollins ‘A West Texas Word List’ in DN IV:iii 229: sour bosom, n. Bacon. Very common. A less elegant variant is sour belly. Frequently one hears at the dinner-table, ‘Pass me the S.B.’.

2. (US) a euph. for son of a bitch.

1924		(con. 1880–1924) F.J. Wilstach Anecdota erótica 40: Owl: ‘Who, Who.’ Parrot: ‘Not you, you s.b.’.
1933		J.T. Farrell Gas-House McGinty 216: He’d hate to be a broad and have to go to that dirty sb.
1980		E. Folb Runnin’ Down Some Lines 128: When your lawyer get dere, den you call ’em a bunch s.b.s.
1980		Jackson & Christian Death Row 201: I was cussing every other breath, every word that come out of my mouth was MF, SB, GD.