The twist? Mak does not know Nak is a ghost. His friends, however, figure it out immediately. The rest of the film is a hilarious cat-and-mouse game where the friends try to warn Mak without getting killed by the ghost—who may or may not know that they know.
The characters speak a mix of Central Thai and the Isan dialect (which is similar to Lao). This is a running gag—Mak’s friends often mock his countryside accent. Good English subtitles will indicate dialect shifts using slang or rural English accents (like Southern US drawls or Cockney rhyming slang). Bad subtitles flatten everything into generic English. Pee Mak English Subtitle