Green’s Dictionary of Slang

sling n.2

[1990s+] (US prison) a belt with a sharpened buckle, used as an offensive weapon.

SE in slang uses

In compounds

sling shot (n.)

see separate entry.

In phrases

get one’s eye in a sling (v.) (also have one’s eye in a sling)

1. [late 19C+] to be depressed, crushed, defeated; thus put someone’s eye in a sling v., to depress someone; with one’s eye in a sling, depressed, crushed, defeated .

2. [1920s] to assault physically.

have one’s head in a sling (v.)

[1940s–60s] (orig. US black) to be defeated or depressed.

have someone’s nuts in a sling (v.)

[1990s+] to have someone at one’s mercy, lit. or fig.

in a sling

[1940s–60s] (US) in difficulties.

put someone’s ass in a sling (v.) (also have someone’s ass/tail in a sling) [ass n. (2)]

[1940s+] (US) to cause trouble for.