Green’s Dictionary of Slang

sling shot n.

1. [1960s] (US) a flick-knife.

2. as a form of under-garment [the shape].

(a) [1980s] (US black) a sanitary towel.

(b) [1990s+] (W.I.) skimpy underwear; a thong.

(c) [1990s+] (US prison) male underwear, briefs; also attrib.

3. [1980s] (US black) a Cadillac Eldorado [ety. unknown].