Green’s Dictionary of Slang

pen yen n.

also ah-pen-yen, pen yan, ...yang, pin yen, ...yuen, pinyon
[Chinese nga pun-yin, opium]

1. (drugs) opium.

Herald (Los Angeles) 3 Sept. 11/2: The vistors [...] explained they wanted to smoke. ‘Bing goye ship goe san ah pin yen,’ muttered the Chinaman.
[US]Courier (Lincoln, NE) 7 Aug. 12/4: Her smile was like ka-pen-yen-see, the Black Smoke, which makes one drunk and dream of heaven.
[US]Tulsa Dly World (OK) 12 Oct. 2/1: No Longer Will the Heathen Chink be Permitted to Enjoy the Seductive ‘Pin Yen’.
[US]G. Bronson-Howard God’s Man 250: He winked so prodigiously this time that Arnold was quite sure this particular ginseng was a euphemism for the forbidden pen-yen.
[US]Bridgeport Times (CT) 3 Apr. 16/3: Not only the Pin yen (commercial opium) was found in the Hop Toys but Yen Shee (ashes), evidence that smoking had been in progress.
[UK]E. Murphy Black Candle 113: Opium ready for smoking is usually about the consistency of black molasses, or of tar. Pedlars call it ‘mud’ but the Chinese name for the mixture is pen yang.
[US]Irwin Amer. Tramp and Und. Sl. 143: Pen Yen.–Opium.
[UK]V. Davis Phenomena in Crime 92: There are three grades of opium. Pin Yen is the finest.
[US]Anslinger & Tompkins Traffic In Narcotics 313: pen yen [...] pinyon. Opium.
[US]Ragen & Finston World’s Toughest Prison 812: pen yen – Opium.
[US]E.E. Landy Underground Dict. (1972) 147: pen yuen [...] Opium.
[US]ONDCP Street Terms 16: Pen yan — Opium. [Ibid.] 17: Pin yen — Opium.
(ref. to 1885) Wave Mag. [Internet] They mounted an 1885 study [...] and found 26 opium ‘resorts’ with a total of 320 bunks. Every resort was given a rating that ranged from ‘filthy’ to ‘very filthy’ with additional notes if the opium, or ‘ah-pen-yen,’ was cooked up at the same den it was smoked.

2. (US drugs) second-rate opium.

Eve, Star (Wash., DC) 1 Sept. 2/5: Raw opium of an infeior grade called by Chinamen ‘pen yen,’ [...] about 70 per cent opium and 30 per cent yen seed.