The King was left slightly taken aback after sipping a premium rum distilled in his honour to celebrate his state visit to Guyana on Thursday.
Charles, 77, was offered a glass of "Royal Welcome" limited edition 2026 rum made by food and beverage company Banks DIH at the start of his two-day visit to the South American country.
Before sampling the drink, he asked guests nearby: "Do you drink this? Endless rum punches at the end of the day?"
He smelled the spirit before taking a swing, before waggling his eyebrows and pulling a surprised face, before declaring: "Very good".
© Getty ImagesPresident Mohamed Irfaan Ali, clearly more accustomed to it, leaned over and told the monarch: "You’ve just got to drink it down!"
"It won’t last long," grinned the King and took another sip, but was clearly worried about having too much alcohol while on duty.
The monarch turned to an aide and appeared to tell them: "I can't drink it," before telling his hosts: "That’s very kind. Somebody else will have to finish it!
"It's a great pick-me-up, as my grandmother used to say," he added, appearing to refer to Elizabeth, the Queen Mother, the wife of King George VI.
© Getty ImagesThe royal family's favourite alcoholic beverages
While he didn't seem entirely convinced by the rum, the King is often presented with alcoholic drinks on public engagements, sampling anything from the finest whiskies to pints.
But what do the other royals enjoy drinking?
© GettyQueen Camilla is known to be partial to red wine – and it appears to be her drink of choice, while Prince William likes cider.
The late Queen Elizabeth's former chef revealed she enjoyed a gin and Dubonnet, while Princess Eugenie enjoys "vodka soda with loads of lime".
Meanwhile, Meghan Markle also likes wine, while Prince Harry is said to enjoy a classic British pub order – a pint of beer.
King Charles's Caribbean tour continues
Charles began his two-day trip to the South American country with a cultural evening hosted by President Mohamed Irfaan Ali after the two men held talks before the entertainment began.
Among the guests were Brits with connections to the country, including pop star Eddy Grant, born in the country before moving to the UK as a child, and former justice secretary David Lammy, whose parents were from Guyana.
Gregory Garraway, Banks DIH’s rum plant executive, said the rum was more than 20 years old, adding: "We wanted the King’s visit to be something he could actually taste.
© Getty Images"Our description of the rum is extremely smooth, rich and flavourful and he loved it."
Charles arrived in the country from the Bahamas for the first leg of his nine-day tour of the Caribbean, which will end in Antigua and Barbuda, where he will reunite with his wife, Queen Camilla.
He is set to open a major Commonwealth leaders' summit in his role as head of the "family of nations".
The trip celebrates Guyana's culture and people, as it marks the 60th anniversary of independence from Britain and comes in the wake of renewed calls from Caribbean nations for Britain to apologise for its role in selling enslaved people for profit and for reparations.
