From the Australian National Dictionary Centre:
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galah
The word galah is a borrowing into Australian English from the Aboriginal Yuwaalaraay language of northern New South Wales. In early records it is variously spelt as galar, gillar, gulah, etc. It is first recorded in 1862 in J. McKinlay's Journal of Exploration in the Interior of Australia: 'A vast number of gulahs, curellas, macaws... here'. The bird referred to is the grey-backed, pink-breasted cockatoo Eolophus roseicapillus, occurring in all parts of Australia except the extreme north-east and south-west. It is also known as the red-breasted cockatoo and rose-breasted cockatoo.
Snip
Very commonly in Australian English galah is used to refer to a fool or idiot. ...
snip ... and the Australian meaning must be a transfer from the bird, no doubt incorporating a judgment about the relative intelligence of the bird.
Snip
From this sense arise a number of colloquial idioms. To be mad as a gum-tree full of galahs is to be completely crazy. To make a proper galah of oneself is to make a complete fool of oneself. A pack of galahs is a group of contemptibly idiotic people.
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If you, like me, are not from "Down Under" you may want to bookmark:
http://www.anu.edu.au/andc/res/aewords/index.php
This will enable you to translate the interactions between Rod and Paul into english. They can be quite quite humorous for those english speakers with facility in foreign languages.
Then we can all be happy little vegemites.
Phil
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