mellow yellow, n. — Green’s Dictionary of Slang

mellow yellow n.

1. (US black) a light-skinned girl or woman; usu. attractive [mellow adj. (4) + yellow n. (1) + assonance].

1980

E. Folb Runnin’ Down Some Lines 141: Terms for a light-complected person – high yellow, melted butter, mellow yellow – were most often seen in a positive light.

2. (also yellow) in drug uses [‘Mellow Yellow’ (1967) a song by hippie n.² (3) folk-singer Donovan + mellow adj. (6)].

(a) dried banana skins, which, according to contemporary rumour, could be smoked.

1968		‘Sl. of Watts’ in Current Sl. III:2 34: Mellow yellow, v. Intoxicated from smoking banana peel.
1969		L. Yablonsky Hippie Trip 138: I accepted one of the ‘mellow yellows’ Bill offered me.
1971		E.E. Landy Underground Dict. (1972).

(b) (drugs, also yellow) a variety of LSD.

1971		E.E. Landy Underground Dict. (1972) 202: yellow [...] LSD.
1977		L. Young et al. Recreational Drugs.
1980		‘Gloss. of Drug Terms’ National Instit. Drug Abuse.
2001		ONDCP Street Terms 15: Mellow yellow — LSD. [Ibid.] 23: Yellow — LSD.

3. (S.Afr. township) a CASSPIR armoured truck, used to maintain order in the townships [the colour of the vehicles, thence the proprietary name of a yellow-coloured soft drink, ult. f. the song, see sense 2].

1996

CyberBraai Lex. at www.matriots.com 🌐 MELLOW YELLOW: A township name for yellow police patrol vehicles.