The Nugget (Australian movie 2002)

Three friends -- the unlucky Lotto (Eric Bana), the naive Wookie (Stephen Curry) and the lazy Sue (Dave O'Neil) -- are road workers by day and gold diggers on weekends. On one trip out in the hills, the three misfits strike it rich when they stumble across a huge nugget of gold worth millions of dollars. After the three friends argue over how to split their findings, they encounter even bigger problems: other gold prospectors know what they found, and they're trying to steal it.