Green’s Dictionary of Slang

1. (drugs) a variety of LSD, in orange-coloured capsules; usu. in combs., e.g. orange barrels/cubes/haze/micro/Owsley (cf. orange sunshine n.).

1971		E.E. Landy Underground Dict. (1972).
1991		B. Hamper Rivethead (1992) 19: We ate acid at every opportunity [...] stoned to the gills on orange barrel mescaline or windowpane acid.
2001		ONDCP Street Terms 16: Orange barrels [...] Orange cubes [...] Orange haze [...] Orange micro [...] — LSD.

2. (N.Z. prison) a 60 mg tablet of morphine sulphate.

2001

D. Looser Boobslang [U. Canterbury D.Phil. thesis] 131/2: orange n. a 60 mg morphine sulphate tablet (MST) [...] orange juice n. a concoction of 60 mg MSTs (oranges) cooked up to extract the morphine.