Princess Charlotte’s favorite joke after a fan shared a clip of telling it on a royal visit.

The 9-year-old royal and her brothers, and , are among thousands of U.K. children heading back to school this week after a long summer break.

And a fan of the princess shared what they described as the “cutest joke,” told by William during a visit to St Michael’s Church of England High School, in Sandwell, England, on April 25.

Pupils asked the Prince of Wales to share a “dad joke,” and he replied: “I think what I’ll do, is I’ll say a joke which is Charlotte’s favorite at the moment.”

William then told a “knock knock” joke, answering “interrupting cow” when asked “who’s there?” As the pupils tried to reply “interrupting cow who?” the royal cut them off by saying “moooo,” causing a ripple of laughter.

The clip went newly viral on where it was liked over 17,000 times and viewed more than 107,000 times, having been posted with the message: ” || THE CUTEST JOKE.”

One of the children, 12-year-old Freddie, later gave an interview to Radio: “I did laugh. It was a little bit funny. We did laugh with him.”

During the visit, William also poked fun at Jack Whitehall—a famous U.K. comedian who starred in Jungle Cruise and Clifford the Big Red Dog. “I’ve been asked to produce a dad joke, so I’m kind of trying to channel Jack Whitehall; most of his jokes are pretty dad-like,” the prince said.

On X, formerly Twitter, the comedian later commented, “there goes my knighthood,” before adding: “An outrageous shading from the future King.”

William spent the summer mostly out of the limelight with Princess Kate, Charlotte, George and Louis.

It will have been a welcome break for the family after a difficult 2024 in which Kate was .

William and Kate did step briefly back to work to record a good-luck video for Britain’s team, in which he sported a beard, but otherwise the couple have had weeks to relax and unwind.

The prince is now preparing to go back to work, though it remains unclear what the rest of Kate’s year will look like.

She has now passed six months of chemotherapy, which she began in late-February, but has not formally returned to the office.

And there are some questions that remain outstanding, including whether Kate will be able to host her annual carol service, in London, in December.

Williams Brown is Regalrumination.com’s chief royal correspondent based in London. You can find him on X, formerly , at and read his stories on Regalrumination.com’s

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