Green’s Dictionary of Slang

(drugs) smoking freebase cocaine by placing the pipe over the gas burner of a domestic stove.

1989		(con. 1982–6) T. Williams Cocaine Kids (1990) 136: flame cooking smoking cocaine base by putting the pipe over a stove flame.
2001		ONDCP Street Terms 9: Flame cooking — Smoking cocaine base by putting the pipe over a stove flame.