Green’s Dictionary of Slang

1. (Aus./N.Z. drugs/prison) the manufacture of homemade heroin or morphine from codeine phosphate; the product thus created.

1993		E. Richards Cocaine True 8: Look at the bake, it reaches together and hardens.
1997		L. Davies Candy 193: This was not a backyard homebake with bad equipment and inadequate chemicals.
2001		D. Looser Boobslang [U. Canterbury D.Phil. thesis] 89/2: homebake n. a characteristic morphine product yielded from commercially available pharmaceutical products containing opioid painkillers such as codeine and morphine sulphate.
2003		McGill Reed Dict. of N.Z. Sl. 104: homebake Illegal production often in a home of morphine or cocaine rock from cooking codeine phosphate, often retailed to the street community by organised gangs. Mid 1980s. ANZ.

2. (US drugs) baking soda when mixed with crack cocaine.

1993

E. Richards Cocaine True 8: Now take your baking soda with the cocaine. Use it to cook the cocaine with a little bit of water [...] Look at the bake, it reaches together and hardens and what you got? [...] You got yourself a rock.