Cabka is a liquor Howard made for Orc, although he also sold it to various others, like Jamal and Turk. It's made by distilling cabbage and rotten oranges, although according to Orc, anything can be used, such as corn and artichokes. Howard distills it inside the Coates Academy. It is described as being a murky liquid.
The name is a mix of the words 'cabbage' and 'vodka'. It is described as being clear and strong-smelling. Orc comments on it saying that it was nasty stuff, but he still drinks it, and it is with this alcohol that he attempts his suicide with, but fails.
Presumably, it is no longer made after Howard's death in Fear.