Green’s Dictionary of Slang

1. (Aus.) the stomach [SE flab].

1918

Aussie (France) 18 Jan. 4/2: Kill! Kill! Kill! / The long point, the short and the jab; / Shove it right into his Sandy McNab, / Stop when he’s permanently still.

2. (also Sandy) a crab, a body louse, usu. in pl.

1968		J. Alard He who Shoots Last 126: Da foist week I wuz here, I cracked it fer a load of da Sandy McNabs; dey nearly drove me yarra.
1984		Partridge DSUE (8th edn) 1011: since early WW1. (Brian Inglis, Spectator, 15 Jan. 1977). ‘A dose of the sandies. Animated dandruff’ (Red Daniells, 1980).
2002		Pete’s Aussie Sl. Home Page 🌐 Sandy Macnabs: the crabs, body lice.

3. (Aus.) a scab.

1972		Dodson & Saczek Dict. of Cockney Rhy. Sl.
1984		Partridge DSUE (8th edn) 1011: since ca. 1920.

4. a taxi-cab.

1960		J. Franklyn Dict. of Rhy. Sl.
1965		F.J. Hardy Yarns of Billy Borker 95: He’s been driving Sandy McNabs for thirty-five years.
1972		Dodson & Saczek Dict. of Cockney Rhy. Sl.
1984		Partridge DSUE (8th edn) 1011: since ca. 1946.