The Australian-English derogatory term coconut (black) is used by some Aborigines of those who are considered to have betrayed their Aboriginal identity in order to be accepted into the white Australian society.

The image is that—like the coconut, dark on the outside, but white on the inside—those Aboriginal ‘betrayers’ are outwardly black, but inwardly white.

These are the earliest occurrences of coconut (black) that I have found, in chronological order:

1-: From Aborigines describe colour bar by stealth, by Malcolm Brown, published in The Sydney Morning Herald (Sydney, New South Wales) of Thursday 24^th September 1981:

Mr Ted Simpson, the north-western NSW representative on the National Aboriginal Conference, has been rejected for membership of the Walgett ¹ RSL ² in an incident he and other Aboriginal leaders say is symptomatic of the increasingly sophisticated forms of racial discrimination in the region.
“The repression here is sophisticated,” he said yesterday. “The reason they are trying to keep me down is that they classify me as a leader.
“There is still discrimination against Aborigines, but now it is not done openly—it is done behind closed doors.”
[…]
Mr Simpson, aged 37, has been a Walgett resident for 17 years and previously worked for the Aboriginal Legal Service.
While some Aborigines were allowed to join RSL, bowling and golf clubs, they were the ones who were acceptable to leaders of the white community and were not representative of the majority of the Aboriginal people, he said.
“We call them coconut blacks—dark on the outside and white on the inside.”

¹ Walgett is a town in northern New South Wales.
² The Returned and Services League (RSL) is a support organisation for men and women who have served or are serving in the Defence Force.

2-: From a story about the “racially torn town” of Moree, in northern New South Wales, by Malcolm Brown, published in The Sydney Morning Herald (Sydney, New South Wales) of Monday 14^th February 1983:

The racial antagonisms are not confined to the whites. There are two Aboriginal words for the races in Moree. One is “murri,” an Aboriginal word for themselves, which is quite acceptable. The other, for whites, is “gubber,” which is derogatory.
A young Aboriginal woman described last month how she walked into a hotel to find a black man drinking alone with whites. She told him sneeringly that he was a “gubber lover.”
Such resentment is not confined to the whites, either. It also applies io some of the Aborigines who have “made it.”
One word used in the north-west is “coconut blacks,” Aborigines who, according to the radical blacks, are “dark on the outside and white inside.”

3-: From a story about Alice Springs, a town in the Northern Territory, by Ben Hills, published in The Sydney Morning Herald (Sydney, New South Wales) of Saturday 2^nd June 1990:

“The other day, an Aboriginal man climbed into a charity clothing bin in the middle of town, and he died before they found him. There was no outcry about that. It was just like an unfortunate dog crawled in and strangled itself, not a human being.” This is one of the best-known and most articulate of the black spokespeople in the Alice, a formidable woman named Rosalie Kunoth Monks.
Like many of the people you talk to here, she regards herself as 100 per cent Aboriginal (“I’m not one of those coconuts, black on the outside and white on the inside”)—although the Kunoth, in fact, was a German grandfather, and the Monks is an Englishman swinging in her husband’s family tree.

4-: From Questioning self-appointed, media-anointed black spokesmen, by Flo Grant, published in The Sydney Morning Herald (Sydney, New South Wales) of Wednesday 3^rd October 1990:

Despite the hardships, the segregation and the discrimination, or maybe because of them, the old generation of Aboriginal people were progressive.
They saw a future in their country and were prepared to lay down their lives, along with white soldiers, to fight for their country.
They had no million-dollar handouts, but they got on with the job of living for the future, not looking back on the past.
They are considered coconuts, black on the outside and white on the inside, or assimilationists by today’s radical activists who want to go back to the bureaucratic control of Aboriginal people through land councils, and to the “dog tags” to prove you are a worthy Aborigine to allocate funds to help develop your people’s self-perception.