R

RAAF
Royal Australian Airforce

RAN
Royal Australian Navy

redback
1. redback spider, also known as the dunny spider, due to its love of lurking in outdoor toilets.

2. Redback beer.

rego
car license number, sticker on windshield giving date of registration

Short for registration.

the rock / the big red rock
Uluru, formerly known as Ayer's Rock

That big red rock in the middle of Australia all the tourists want to visit. If Australia has a physical heart, Uluru is it.

roo
kangaroo

The western reds are the big ones. Like that one in that appalling movie Kangaroo Jack, which incidentally was not an Australian movie. It was just filmed here by some bloody Hollywood crowd. The grey kangaroos are either eastern greys (smaller) or wallabies (smaller than eastern greys).

root
screw, fuck, make the sex, have sex

We do not root for our teams, we barrack for them. They can root for themselves.

RSL
Returned and Services League

Formed during World War I "to perpetuate the close ties of friendship created by mutual service in the Australian Defence Force or allied forces, to maintain a proper standard of dignity and honour among all past and present serving members of the Defence Force". Nowadays the NSW RSLs look a lot like casinos. The ones in Perth (WA) are still more like Senior Citizens clubs.