Britain's Prince William told Lee Mack "to get some new jokes".
The 31-year-old royal once left the stand-up comedian feeling red-faced after he shot down one of his gags during a visit to Buckingham Palace in London.
Speaking on the 'Graham Norton Show', Lee explained: "That was a bit of highlight. We got to go to the Palace, which was very exciting and he came up to me and said, 'You need some new jokes.'"
However, the 53-year-old star - who has his own show 'Not Going Out' - was left feeling even more embarrassed when he hit out at the second-in-line to the throne in a sarcastic tone for criticising his career.
He explained: "I was a bit drunk and said, 'I don't tell you how to be a future king,' to which he said, 'I was joking, I really like your sitcom.' I felt a bit bad then."
Fellow guest Sir Kenneth Branagh also spoke about his Buckingham Palace experience as he collected his knighthood in 2012, saying how petrified he was of standing on the small Welsh Corgi dogs.
He said: "We had an amazing day - going to Buckingham Palace is quite something - but I was terrified.
"Terrified of stepping on dogs, the corgis are everywhere, so I was quite nervous of kneeling on one."
'The Graham Norton Show' will air on Friday (24.01.14).
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