Prince William galloped in the royal box at the Royal Variety Performance.
The 35-year-old royal was asked by one of the young members of the 'Annie' cast to try out his galloping after being encouraged to put forward the comic request to the prince by host Miranda Hart.
William - who has two kids, Prince George, four, and two-year-old Princess Charlotte, with wife Duchess Catherine - responded by impersonating a horse running at a quick pace.
After the star-studded event - which was broadcast on ITV last night (19.12.17) - Miranda praised William for joining in with that and some of her other comic requests, including shouting out her catchphrase "such fun" whenever she asked him to.
She said: "It was a great celebration of mood-lifting work.
"I did apologise to him at the end and he said he'd practice his galloping. I thought he was wonderful in joining in. I forgot to get him to knight me with a lightsaber but maybe another time."
William was joined by Catherine at the London Palladium event and they were the focus of a number of quips, including one from the cast of sitcom 'Miranda'.
Patricia Hodge looked up at the royal pair with binoculars and asked the audience: "Can you believe they've got an iPad and their watching 'The Crown'?
"It's their version of 'I'm a Celebrity Get Me Out Of Here'."
Afterwards, William joked he was going to hit the gym a bit harder to be more like performers from Cirque du Soleil.
He said: "You were incredible. I could never do it - I'll have to go to the gym a bit more and work on my core."
Several stars performed at the spectacle, including The Killers, Louis Tomlinson, Michael Ball and Paloma Faith.