Prince Harry's risqué comment about his injured manhood leaves Stephen Colbert grimacing

Prince Harry has left a television host in stitches when he recalled a risqué story from his book Spare.

The Duke of Sussex appeared in front of an audience for the first time as he joined host Stephen Colbert on The Late Show.

It was Harry's final television interview in promotion of his memoir and was filmed in New York on Monday, airing on Tuesday in the US, the day his book was officially published around the world.

Harry discussed a range of topics from Spare, including his time serving in the British Army, his memories of the late Queen Elizabeth II, life with Meghan in California and how his manhood got injured during a trek to the North Pole – a reveal that left Colbert gobsmacked.

Watch the video above.

READ MORE: Key moments from Harry's The Late Show interview

"Can I have a drink?" Harry asked, as he launched into a story about his "todger" that got "frostnip" during a trek to the North Pole ahead of Prince William's wedding in 2011.

Moments earlier, Colbert had offered "a cocktail" before launching into into the chat, remarking, "I've heard you like tequila".

"It's really hard to have this conversation," Harry laughed, saying no-one in the audience had the chance to read the book for the anecdote's context.

"It's fine now, thank you," he said, when Colbert asked whether his privates had healed.

Harry explained he was joining a group of wounded veterans for the trek, who had all taken part in training for the conditions which plunged to minus 35 Degrees Celsius.

READ MORE: Harry wears necklace broken in fight with William on The Late Show

That included wearing specialised clothing to prevent sweat, which was a major cause of frostnip as any moisture instantly freezes.

So when he embarked on a trek to the South Pole, a few years later, Harry said he was better prepared.

That included wearing the correct protective clothing, including "a c--k cushion" a friend had made especially for him.

Colbert laughed, took off his glasses and put his head in his hands as the duke made the extraordinary revelation about his nether regions.

"No-one in my life, as a child, could ever explain to me that someday the Duke of Sussex would say the words 'c--k cushion' to me and it would all make sense. It's so surreal."