The Oxford English Dictionary describes it as "an act of exposing one's buttocks" and cites its earliest published use as 1990, writes Tony Tysome.
But researchers for the BBC television programme Balderdash and Piffle have traced the first written record of the word "moonie" back to three years earlier, at Leicester University.
Researchers tipped off by Leicester alumni were able to confirm that the first known use of the word in print appeared in the Leicester student newspaper Ripple , on November 13, 1987.
A notice in the newspaper's Rag Week edition advertises the services of "The Moonie Squad", adding: "For a payment of £3, the bare cheeked boys return to horrify you with their behinds."
Although it is clear that the word was in common use long before the 1980s, no earlier written record has so far been found.
The OED , which uses a different preferred spelling of the word, refers to an extract from Anthony Beevor's Inside the British Army , published in 1990, which describes a sapper captain's anger over one of his officers being "busted for doing a moony" in front of a barmaid. The dictionary entry will be amended in the light of the Leicester discovery.
Ripple 's current editor, Aaron Porter, an English literature student, said he was "delighted" that the newspaper had made a verifiable contribution to the variety and vitality of the English language.
"It is nice to find that we have helped give the word, although humorous, some recognition," he said.
"I take the Oxford English Dictionary as my personal gospel, so I would see no problem now with using the word in an essay," Mr Porter added.
A spokesman for Leicester, which is the base for the national English Association, said: "It is pleasing that the students have continued adding to the richness of the English language."
Leicester's linguistic claim to fame will feature in BBC Two's next screening of Balderdash and Piffle , on Sunday.