Green’s Dictionary of Slang

Tennant creek n.

(Aus.) a Greek.

1985		B. Humphries Traveller’s Tool 38: There’s a Tennant Creek behind the wheel of most Australian taxi-cabs.
1999		G. Seal Lingo 90: Some other examples: [...] tennant creek means a Greek (Northern Territory); werris creek (Victoria and New South Wales) also a Greek, usually just werris.