Pull My Daisy (The Beat Generation) (1959): Directed by Robert Frank and Alfred Leslie. Written and narrated by Jack Kerouac. (via UbuWeb)

Here's a part of the description of the film in Wikipedia:

Pull My Daisy is a short film that typifies the Beat Generation. Directed by Robert Frank and Alfred Leslie, Daisy was adapted by Jack Kerouac from the third act of a stage play he never finished entitled Beat Generation. Kerouac also provided improvised narration. It starred Allen Ginsberg, Gregory Corso, Larry Rivers, Peter Orlovsky, David Amram, Richard Bellamy, Alice Neel, Sally Gross and Pablo Frank, Robert Frank's then-infant son.

Based on an incident in the life of Neal Cassady and his wife Carolyn, Daisy tells the story of a railway brakeman whose painter wife invites a respectable bishop over for dinner. However, the brakeman's bohemian friends crash the party, with comic results.

The Beat philosophy emphasized spontaneity, and the film conveyed the quality of having been thrown together or even improvised. Pull My Daisy was accordingly praised for years as an improvisational masterpiece, until Leslie revealed in a November 28, 1968 article in the Village Voice that the film was actually carefully planned, rehearsed, and directed by him and Frank, who shot the film on a professionally lit studio set.