Airplane! (1980) (good year)

About 20 minutes into the film is a moment which tells you exactly what sort of movie 'Airplane!' is. The stewardess is singing a song for a sick girl on the plane. Everyone on the plane smiles and looks up in a cutesy sort of moment. Then, during a shot of the aisle, a man hanging upside-down from the ceiling lowers himself into view and smiles in the same fashion.
The rest of 'Airplane!' is just like that scene: unabashedly silly. Each scene is full of nonsensical jokes. Not every one is a hit out of the park, but in a movie with hundreds of similarly silly jokes, more than enough are to enjoy the film. Plus, it doesn't hurt to have probably the funniest one-liner of any movie I've ever seen.