Prince Harry held up pair of underpants in room full of shocked royals at William's wedding.
The act is the latest in a series of revelations which have emerged in Prince Harry 's book 'Spare' which has been released in Spain.
In an earlier translation of the book, he recalled suffering from icy injuries to his manhood.
Now it has emerged he astonished members of the Royal Family by holding up a pair of Tanga briefs.
In the new translation of the Spanish passage, Harry explains he was asked to compere and introduce 'the two real best men' before holding up the pair of underpants.
The move was designed to lighten the mood and encourage laughter among guests, but shocked others in the Royal Family.
In the book translation Prince Harry writes on p263: "I went on to say that the Yankee improvised and did the best he could, as they usually do, and I held up the item in question.
"The entire room gasped.
"It was a thong.
"A soft, furry piece of ermine fur in the shape of a V, not much bigger than the pocket of her tunic where she kept the ring, on several silken cords.
"The astonishment gave way to a wave of warm, gratifying laughter."
Earlier the Duke of Sussex revealed he was suffering from a frostbitten penis during Prince William and Kate Middleton 's wedding — and that he is circumcised.
In the 'tell-all' memoir, the royal makes a number of personal revelations in the book — including putting to rest long-running rumours about his manhood.
The autobiography will not be released in the UK until Tuesday, but excerpts from the book have leaked ahead of its release after it was accidentally sold early in Spain.
In one section, he detailed his painful experience with frostbite — which he said affected his ears, cheeks and 'todger' — following a 200-mile Arctic charity walk.
The prince's Walking with the Wounded expedition saw him embark on a brutal journey to the North Pole alongside four ex-servicemen who were injured in Afghanistan.
The team raised £2 million for the Walking with the Wounded charity during the 13-day treck, but the journey didn't come without its downfalls.
In his book Harry reveals that while standing by Prince William's side during his wedding on April 29, 2011, he was actually still recovering from the icy injuries, Page Six reports.
The Mirror reported yesterday how Prince Harry will “never be forgiven” for revealing details of intimate conversation with his father King Charles and brother Prince William insiders have said.
Sources close to the royal family said the Duke of Sussex would be branded a “traitor” because of Spare, which includes allegations that William attacked him as they argued about Harry’s wife Meghan.
A former royal staffer, who knew William and Harry while working in the household, said there would “never be a way back for Harry”.
The source said: “I believe he will never be forgiven. After everything he has said about privacy and intrusion, this is hard to comprehend. His words are so vicious and targeted.
“I don’t doubt he still loves his father and his brother but it’s impossible to see how he won’t come to bitterly regret his decision to do this.
“He knows he will be labelled a traitor, by crossing a red line so many times, his father, his brother, the Princess (of Wales) and Camilla, it’s utterly extraordinary.”
