Green’s Dictionary of Slang

1. (Aus.) a curry.

2002

Pete’s Aussie Sl. Home Page 🌐 River Murry: a curry.

2. (Aus.) in pl., phr. of affirmation, assurance, encouragement [River Murrays = no worries (mate) phr.].

1998		R.G. Barrett Mud Crab Boogie (2013) [ebook] ‘No River Murrays, Vadim.’ ‘Is what?’ ‘No worries’.
1999		G. Seal Lingo 90: Some other examples: [...] river murrays (No) or no worries.