This is Spinal Tap
A film like This is Spinal Tap wasn’t supposed to be taken so seriously with its fake UK band and Americans pretending to be 80’s rockers. Most of the movie was actually the cast inventing stuff. Since the actors came up with so much of the film, they were credited as writers. So yeah even, “It’s such a fine line between stupid and clever,” was improvised.

This Is Spinal Tap
Dr. Strangelove
Apparently, they almost called Dr. Strangelove, “How I Learned to Stop Worrying About the Bomb.” From the very beginning, this film was made as an absurdist piece. The film centered on nuclear war paranoia. Actually, the movie team chose to not write a standard, full script. All of the cast improvised and created something called a ‘retro-script’ where they combined those lines. However, the film’s most iconic thing has to be the Nazi salute from Dr. Strangelove.

Dr. Strangelove