Green’s Dictionary of Slang

1. national service.

1966		B. Beaver You Can’t Come Back 5: Sam, the new one, was just eighteen and due for his Nasho training [GAW4].
1986		C. Bowles G’DAY 19: When you’re off working you might be doing a bit of bizzo, unless you’re in the army when you're doing nashos.

2. a national serviceman.

1954		Bulletin 20 Oct. 9: ‘I’m a Nasho,’ he said. ‘Got a bivouac this weekend.’.
1962		C. Rohan Delinquents 52: She seemed to know every Nasho in Brisbane.
1975		D. Malouf Johnno 70: Now the Grand Central was the drinking place of ‘Nashos’.
1986		R. Beckett Dinkum Aussie Dict. 37: Nasho: One who in past years was forced to serve his country for his country’s good. Short for National Serviceman.
1995		(con. 1965) Canberra Times (ACT) 30 July 19: [headline] A Nasho at Pucka. Paul Weaver recalls his experience as a national service conscript.