Green’s Dictionary of Slang

dipper n.⁴

[? the dipping of the yen hock under yen n.¹ into the bowl of the pipe prior to lighting the opium]

(US drugs) an opium pipe.

1949		Monteleone Criminal Sl. (rev. edn).
1953		Anslinger & Tompkins Traffic In Narcotics 307: dipper. An opium pipe.