Green’s Dictionary of Slang

1. (Aus.) an Egyptian coin.

1918

Kia Ora Coo-ee 15 Apr. 20/2: ‘But I’ll bet you fifty dizzies you can’t raise spirits from the Desert.’ / ‘Done,’ cried Morton. ‘Hand over the feloush.’ [Ibid.] 15 May 6/2: [He] tossed the driver a ten dizzy piece.

2. (N.Z. prison, also dizzy lizzy) a $20 note.

2001

D. Looser Boobslang [U. Canterbury D.Phil. thesis] 57/1: dizzy (also dizzy lizzie) n. a $20 note.