They're all wrong. In 1910, Horace de Vere Cole, a British aristocrat (centre), contacted the Admiralty pretending to be the Emperor of Abyssinia and told officials that he wished to inspect the Home Fleet while on a forthcoming visit to Britain. After enlisting some friends from the Bloomsbury Group, including Virginia Woolf, (far left with turban) they all dressed up in silly costumes and boot-polish and masqueraded as his entourage while on an 'official visit' to HMS Dreadnought. During the inspection, the 'visitors' cried 'Bunga, Bunga!' in appreciation. They were treated to a civic reception afterwards.
The phrase exists in other languages - it means 'flowers' in an Indonesian dialect - but, for now, 'bunga bunga' seems to belong to the Italian Prime Minister.