Green’s Dictionary of Slang

oranges n.

[the colour of the pills]

(drugs) amphetamine.

1967		J.B. Williams Narcotics and Hallucinogens.
1977		L. Young et al. Recreational Drugs.
1981		D.E. Miller Bk of Jargon 338: oranges: Amphetamines.
2001		ONDCP Street Terms 16: Oranges — Amphetamine.