Green’s Dictionary of Slang

cabbage n.4

[? cabbage n.1 (1), tailors’ scraps, thus ‘padding’; ? OF cabuse, imposture, trick; cabuser, to deceive, to cheat; also OF cabas, cheating, theft; Fr. cabasser, to pack up, to cheat, to steal; cabasseur, deceiver, thief; ‘but evidence is wanting’ (OED)]

1. [early 19C] deceitful talk.

2. [mid–late 19C] a ‘crib’ or other form of cheat used by schoolchildren.