Maneka

We need a flick where King Arthur wakes in modern Jamaica and is very confused.

I think that would be so much funny. He wakes up on a remote beach in Jamaica and he only speaks/understands Brythonic and Medieval Latin. Locals assume he was a tourist who fell from a cruise ship or received a head injury and floated away from a resort. The authorities cannot match his description to any missing persons reports and his fingerprints and DNA produce no hits on INTERPOL. They suspect he may be Welsh or French because the language he speaks resembles Welsh or Breton but France and the UK both state he is not a citizen of their country. Stateless and deeply confused, he is taken in by the community near the beach where he was found, being cared for by a number of local families and doing odd jobs. He slowly learns English and adjusts to the contemporary world, uncertain if his belief that he is the legendary King Arthur was formed by whatever traumatic event caused him to end up Jamaica or if he is actually King Arthur and Prydain is in eminent peril. Mysterious letters from Morgan begin to reaffirm his belief he is King Arthur. He must choose between staying in Jamaica and continuing the happy life he has made for himself or finding a way to get back to Britain without any documentation.

ancient king white boy stuns locals by ordering in perfect Jamaican Patois

He gets to Britain and everyone expects him to sound like a posh noble Englishman because that is the picture Malory painted but he prefers to speak Welsh and when he has to speak English, he speaks with a thick Jamaican accent.