Green’s Dictionary of Slang

lemac n.

also little man
[backsl.]

(US prison) a Camel cigarette.

[US]E. Little Another Day in Paradise 257: He looks at the pack of smokes [...] and says, ‘Got a Lemac?’.
[US]Other Side of the Wall: Prisoner’s Dict. July [Internet] Lemac: A camel cigarette. Also, ‘little man’ (archaic).