When traveling and scuba diving my way around Fiji, New Zealand, Australia, I met people who had these great sayings. Why do people there say "Bob's your uncle" ?

Why is the government referred to as "Uncle Sam" in the USA?

Why do people say "uncle" when they give up in a wrestling match?

I'm sure if you put those phrases into Google (with the quote marks round them), you'd get lots of answers.

The first one is British in origin, from the late 19th century, when the Prime Minister (Robert Cecil, Lord Salisbury) promoted the ministerial career of his nephew. Hence 'Bob's your uncle' now just means you're all set, going the right way, etc.

From: http://www.wordorigins.org

SAY UNCLE:
The OED2 includes a cite from American Speech in 1976 where the origin is traced to the Irish anacol, meaning an act of mercy or quarter. So, to say uncle appears to be a folk etymology that arose in North America from Irish immigrants. The phrase is pretty much unknown in the UK and Ireland.

UNCLE SAM:
The most famous image of Uncle Sam is from James Montgomery Flagg's WWI recruiting poster. But Sam was not the creation of Flagg. Uncle Sam predates Flagg's poster by over a century and is the product of a different war.

The earliest surviving use of the term is from the Troy, NY Troy Post of 3 September 1813:
'Loss upon loss,' and 'no luck stiring but what lights upon Uncle Sam's shoulders,' exclaim the Government editors, in every part of the Country ... This cant name for our government has got almost as current as 'John Bull.' The letters U.S. on the government wagons &c are supposed to have given rise to it.

But legend has it that the name derives from a real man, and the origin is much akin to that of Kilroy. Samuel Wilson, so goes the legend, was a meat inspector in the service of the federal government whose task it was to approve the quality of meat bought by the army. Workers handling barrels of meat stenciled with "US" questioned what the cryptic phrase went. The joke went up that it stood for Uncle Sam Wilson. There is, unfortunately, no evidence to support the story.

The exact origin is lost in history, but it undoubtedly arose as a joke on the paternal nature of the government.

I would assume there is no Uncle Bob in Fiji because of language, SO is there an Uncle Bob in New Zealand or Australia?

Well, I'll be a monkey's uncle. What an unusual topic.

Hmmm, somebody's been reading a little too much "why are you called American" thread here...