Green’s Dictionary of Slang

1. (US Und.) a pimp.

1929		M. Dixon ‘All Around Mama’ in Oliver Screening the Blues (1968) 206: Had a man, good old sweetback, said that I should know, / Said he didn’t do no loving ’lest he had some dough.
1939		D. Maurer ‘Prostitutes and Criminal Argots’ in Lang. Und. (1981) 117/1: box-coat. A pimp. Also [...] Latin lover, Louis, lover, mack, McGimp, salmon-man, star boarder, sweetback.

2. (US black, also pie-back) a womanizer, a ladies’ man.

1928		C. McKay Home to Harlem 283–4: He’s a sweet-back, all right, but he ain’t a strong one.
1929		T. Gordon Born to Be (1975) 77: Every niggah in St. Paul had a sweetie of some kind; sweetbacks had chains of them.
1930		J.W. Johnson Black Manhattan 217: On February 2, 1929 a play was put on at the Apollo Theatre [...] called Harlem and it was a portrayal of life in a Harlem railroad flat, of rent parties, of the ‘sweetback,’ of the ‘hot stuff man,’ of the ‘number king’ and the number racket.
1941		A. Lomax Mister Jelly Roll (1952) 18: They were sweetback men, I suppose you’d call them – always a bunch of women running after them.
a.1948		(con. early 1930s) C. McKay Harlem Glory (1990) 52: Stop kidding, sweet-back [...] Can’t I see you’re on easy street, you hot dog. [Ibid.] 63: I was becoming like a cheap sissified sweetback.
1954		(con. 1920s–30s) J.O. Killens Youngblood (1956) 411: If the New York women love him like the Georgia ones, he musta been a really sweet daddy up there. A pie-back from way back.
1968		I. Reed Free-Lance Pallbearers 33: I’m sick of dem sweetback-looking white mens on my wall.
1971		M. Van Peebles Sweet Sweetback’s Baadasssss Song [film title].
2002		‘Touré’ Portable Promised Land (ms.) 154: We Words (My Favorite Things) [...] Sex machine. Sweetback. Skins.