Green’s Dictionary of Slang

(drugs, also pipe up) to smoke crack cocaine; thus piping n. and adj.

1992		R. Price Clockers 7: Girl wants to pipe up, it’s a free country.
1993		R. Shell Iced 7: I need my $10 so I can pipe later.
2000		J.J. Connolly Layer Cake 63: I know exactly what he looks like — [...] Like a million other pipin niggers.
2000		M. Manning Get Your Cock Out 41: The Chinaman returned with a small silver tray laden with a generous supply of crack cocaine. The Mince piped up.
2002		Guardian 30 May 🌐 Take proper amounts of time out between pipes; and, instead of piping, smoke crack in joints or chase it off foil so that come-downs are less severe. [...] Instead of piping he pursues hobbies including coarse fishing and volleyball.
2011		J.J. Connolly Viva La Madness 42: She starts pipin, smoking stones. Crack!
2020		G. Krauze What They Was 34: Some having just piped up and smoked a rock.