Green’s Dictionary of Slang

(S.Afr.) a pocket-knife.

1974		J. Matthews The Park and Other Stories (1983) 38: ‘Der law pick me up an’ I haf my lem on me. Dey charge me wit’ dangerous weapon. [...] I know how to use a lem. You ever use a lem?’ He crouched, grabbed his back pocket and swayed from side to side making stabbing motions.
1983		J. Matthews The Park and Other Stories (2nd edn) 44: I doan mind to go to jug if I robba outie or stick him witta lem but I doan go to jug for rape.