Green’s Dictionary of Slang

autograph n.

(US drugs) a narcotic injection [it is ‘written in blood’].

[US]J.E. Schmidt Narcotics Lingo and Lore.

In phrases

sign an autograph (v.)

(N.Z. prison) to pass a false cheque.

[NZ]D. Looser Boobslang [U. Canterbury D.Phil. thesis] 167/1: sign an autograph to pass a false cheque.