Green’s Dictionary of Slang

(US black) well-dressed.

1967		C. Cooper Jr Farm (1968) 93: Little Junior came in, decked out with a chintzylooking little blue tie.
1970		B. Seale Seize the Time 143: He had his men all around him, decked down, sharper than a motherfucker.
1972		D. Claerbaut Black Jargon in White America 62: decked adj. dressed well; attractively clothed.
1977		Eble Campus Sl. Fall 2: That dude was decked for the performance.
1980		E. Folb Runnin’ Down Some Lines 111: Expressions reserved for being extraordinarily well dressed (clothed heavy, dapped to a tee, decked to death [...] sharp as a mosquiter’s peter). [Ibid.] 234: decked to death, decked to kill Exceptionally well-dressed [...] Man, dat dude is decked to kill!
1983		G. Tate ‘King Sunny Adé’ in Flyboy in the Buttermilk (1992) 58: We got Nigerians decked to the nines in exquisite Cultural Attire.
2002		W.D. Myers Handbook for Boys 52: He was decked down tough and had gold in his mouth.