what does ranger redhead mean for Australians?

as a 7th generation red headed Australian, i think i am qualified to answer..... Australian's love irony and rhyming slang and testing people to make sure that they don't take themselves too seriously (called taking the piss with good humour!!) soooooo.....

Orang-Utan = an auburn haired primate= becomes "rangga" for Red heads.

Bluey--irony for red (but many red heads in Australia have blue eyes) and matches nicely with the fact that in Australian slang a "Blue" is a fight and that many Red headed Australians have Irish or Scots ancestry.

Blood nut- a "nut" is slang for head,

Meggs--from "Ginger Meggs" an old Australian strip cartoon series (also inclined to fighting)