dro
n.— «In another call, dro is slang for marijuana. Pacman: “Bring that dro over here when you come too buddy.” Moore: “Do what?” Pacman: “Bring some of that Dro when you come over here.” Moore: “I ain’t got none.”» —“Recordings Link Pacman To Drug Dealer” WTVF-TV (Nashville, Tennessee) Feb. 27, 2007. (source: Double-Tongued Dictionary)
Is “dro” derived from “hydro” to refer to hydroponically grown – and presumably high quality – marijuana?