Green’s Dictionary of Slang

(drugs) a smoker of crack cocaine.

[1830		Egan Finish to the Adventures of Tom and Jerry (1889) 76: I am also more of a piper [i.e. of tobacco] than a cigar hero].
1993		E. Richards Cocaine True 15: She’s a piper.
1997		C. Newland Scholar 261: Pipers who’d normally confined their activities to the nocturnal hours began to feel the long, slow roast, due to rocks as much as the heat.
2001		J. Stahl Plainclothes Naked (2002) 288: Zank is a major piper. He hears voices telling him to buy a steak knife and X out pretty white girls, it could be a shitstorm.