They don't call it Sin City for nothing.

During a bender that will live in royal infamy, Prince Harry, fresh from a booze-soaked getaway with pals on Necker Island, tore through Las Vegas and ended up at a game of strip billiards -- with the shocking nude photos, taken Aug. 20, going completely global a few days later.

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The 27-year-old redhead "had two things in his sights: vodka and women," fellow Vegas partier Melissa Vagner tells the new Us Weekly, out now, which has all of the jaw-dropping details on Harry's wild weekend.

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Adds another woman who partied with Prince William's little brother: "He was naked for a long time at the party . . . He didn't seem to care what he did."

The cover story -- which hits newsstands Friday -- also reveals how his stern grandmother Queen Elizabeth II reacted, how it could affect his military career and how the memory of his late mother Princess Diana factors in.

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Pick up the new issue today!

This article originally appeared on Prince Harry Had "Vodka and Women" on His Mind in Las Vegas