Bringing Up Baby - "Gay All of a Sudden"

A 1930s romantic comedy starring Cary Grant playing a disgruntled paleontologist and Katharine Hepburn playing a troublesome heiress. When Susan takes David's clothing he is forced to wear a negligee and answer the door. Here he meets Mrs. Random, the woman he was supposed to make a good impression on so she would give the money to the museum. Argueablely this is the first film where the word "gay" had been used to describe homosexuals (at the time homosexuals had called themselves that but it hadn't gone mainstream) in a film. This was an ad-libbed line that Cary threw into the scene.