Harry's comments were aired on a US chat show this week, with the royal answering 15 light-hearted questions.
He joined the likes of U2 singer Bono and former first lady Michelle Obama in completing the Colbert Questionert when he was a guest on The Late Show With Stephen Colbert.
Asked if he had ever requested someone's autograph, he replied: "Yes, the England rugby team in 2003... at the World Cup final after a few drinks wearing an England rugby top.
"I was going, 'Jonny, Jonny, Mike, Mike, Lawrence come on sign my shirt'."
Harry was in Sydney to watch the England squad, who included Jonny Wilkinson, Lawrence Dallaglio and Mike Tindall, beat Australia in the Rugby World Cup final.
"And they're all there standing naked with their willies hanging out - but I got all 15 signatures and was really happy with that."
Harry smiled when Colbert quipped, "They signed it with pens, yes?"
Tindall married the duke's cousin Zara Phillips in 2011 after Harry is said to have introduced the couple.
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