Here's the scene that ruined the movie David and I wrote, VOLUNTEERS. Tom Hanks stars as a preppy who ducks a gambling debt by joining the Peace Corps in Thailand. We established a character (Lucille) whose English was so bad we needed subtitles. In this scene, played pretty much as written, the director made one change. He had the characters break the fourth wall and read the subtitles.
We argued that it destroyed the reality of the film. There was now no jeopardy. It became a Hope-Crosby Road Picture where the fish could talk. The director argued that it got a big laugh. Why would we want to remove a big laugh? The answer is that it destroys the movie.
Oh, and her make-up was pretty ridiculous. But that we could live with.
The lesson here is never sacrifice the integrity of your piece for the sake of a joke, no matter how funny the joke is.
Billy Wilder used to say, "Why do they remake good movies? They should remake okay movies and make them better." John Krasinski as Lawrence Bourne anyone???