“Airplane [1]” is one of the funniest movies ever made and it still holds up over 35 years later. Most people think it's a parody of all the airline disaster movies of the 70s, but in reality, it's a remake of a 1957 dramatic movie played straight [2] (which explains why the main character is a World War II fighter pilot in a movie made in 1980).
[1] http://www.imdb.com/title/tt0080339/