Magical Mystery Tour
The first critically panned and commercially unsuccessful film the Beatles made, this made-for-TV film is so sixties you get a contact high just WATCHING it. Paul came up with the idea as a project to help keep the band going after the death of their manager Brian Epstein. The lads pretty much made up the "script" as they went along and filmed whatever happened to take place as they tooled around in a blue-and-yellow bus. It's since been re-evaluated for its somewhat proto-Python comedy, and the music is definitely a plus (the soundtrack album was the only successful part of the whole venture), but a LOT of mileage could be gotten out of it.
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Rich T. Anderson commented
Yes. Please!