The Out-of-Towners (1970) was my introduction to Neil Simon. After seeing that movie, I read all his plays: Barefoot in the Park, Plaza Suite, The Odd Couple, The Sunshine Boys, etc. Simon inspired me to become a playwright and a comedy writer. There's nothing like watching something you wrote performed on the stage and to see the audience's reaction.
Interestingly, the movie was not adapted from a Neil Simon play, but was written as an original screenplay.
The Out-of-Towners is absolutely hysterical thanks to Jack Lemmon's magnificent performance. He and Sandy Dennis play George and Gwen Kellerman, a couple from Ohio who are visiting New York City where George is meeting with the New York Division of his company to discuss a job promotion and relocation.
The Kellermans experience one nightmare after another -- losing their hotel reservation, getting mugged, no transportation, no luggage, breaking a heel, losing a tooth, running from the police. They have no place to sleep, no clean clothes, no money to call for help.
I would say this rates as one of the funniest movies of all time.
What movie inspires you?