In Korea, it's the number 4 that does it for them... the word for four is "sa", which is also the first syllable of the word for death, "sa-mang". So Korean elevators show floors 1, 2, 3, 5, 6...

"Sa" is also the unifying syllable among all the names for Buddhist temples ~ Pomosa, Pulguksa, etc... one day a friend and I decided to get off the subway to explore a temple that we could see from the subway stop on the side of a hill above us. We got a taxi near the subway station and gestured wildly in the direction we wanted to go, repeating "Sa, sa, sa" and the names of various temples, hoping the driver would get our meaning. Neither of us knew the name of the temple we were trying to reach, nor the standalone word for temple, nor did we recognize the absurdity that our driver must have felt at a couple of American chicks in the back of his cab screeching "Four, Four, Four!" at him! I'm confident he's still getting mileage out of that story!