Green’s Dictionary of Slang

(US Und.) a plain clothes policemen.

1930		R. Whitfield Green Ice (1988) 16: It wouldn’t take long for the quiet-clothes boys to put two and two together.
1931		R. Whitfield ‘About Kid Deth’ in Penzler Pulp Fiction (2007) 276: Talk to the quiet clothes bull a little.

see lone duck n.

(US black/L.A.) Venice, California.

1980

E. Folb Runnin’ Down Some Lines 251: Quiet Village reference to the black community in Venice, California.

see good woman under good adj.¹

(US black) a phr. used to request secrecy after making a revelation.

2000

Ebonics Primer at www.dolemite.com 🌐 quiet is kept Definition: to keep something a secret Example: Yo, quiet is kept, but , I busted a nut up in this bitch.