Funny, You Don't Look Abyssinian: The Dreadnought Hoax

Wiki:

The Dreadnought Hoax was a practical joke pulled by Horace de Vere Cole in 1910. Cole tricked the Royal Navy into showing their flagship, the warship HMS Dreadnought to a supposed delegation of Abyssinian royals. The hoax drew attention in Britain to the emergence of the Bloomsbury Group.

The hoax involved Cole and five friends— writer Virginia Stephen (later Virginia Woolf), her brother Adrian Stephen, Guy Ridley, Anthony Buxton and artist Duncan Grant—who disguised themselves with skin darkeners and turbans. The disguise's main limitation was that the "royals" could not eat anything or their make-up would be ruined. Adrian Stephen took the role of "interpreter".

On 10 February 1910 the trick began. Cole had an accomplice send a telegram to HMS Dreadnought which was then moored in Weymouth, Dorset. The message said that the ship must be prepared for the visit of a group of princes from Abyssinia and was purportedly signed by Foreign Office Under-secretary Sir Charles Hardinge.

Cole with his entourage went to London's Paddington station where Cole claimed that he was "Herbert Cholmondeley" of the UK Foreign Office and demanded a special train to Weymouth. The stationmaster arranged a VIP coach.

In Weymouth, the navy welcomed the princes with an honour guard. Unfortunately, nobody had found an Abyssinian flag, so the navy proceeded to use that of Zanzibar and to play Zanzibar's national anthem. Their visitors did not appear to notice.

The group inspected the fleet. They distributed cards printed in Swahili and talked with each other in a broken Latin. To show their appreciation, they yelled invented words. They asked for prayer mats and bestowed fake military honours on some of the officers. One officer familiar with both Cole and Virginia Stephen failed to recognize either one, possibly because he heard the interpreter's strong German accent and was worried in case a German spy came on-board.

When they were on the train, Anthony Buxton sneezed and blew off his false whiskers, but managed to stick them back before anyone noticed. Cole told a train conductor that he could serve royals lunch only with white gloves. This was, of course, to avoid the problem with the make-up.

In London, they revealed the ruse by sending a letter and a group photo to the Daily Mirror. The Royal Navy briefly became an object of ridicule and demanded that Cole be arrested. However, Cole and his compatriots had not broken any law. The Navy sent two officers to cane Cole as a punishment—but Cole countered that it was they who should be caned because they had been fooled in the first place.