Rain Man is a 1988 American drama film directed by Barry Levinson and written by Barry Morrow and Ronald Bass. It tells the story of an abrasive and selfish young wheeler-dealer, Charlie Babbitt (Tom Cruise), who discovers that his estranged father has died and bequeathed all of his multimillion-dollar estate to his other son, Raymond (Dustin Hoffman), an autistic savant, of whose existence Charlie was unaware. Charlie is left only his father's car and his collection of rose bushes. In addition to the two leads, Valeria Golino stars as Charlie's girlfriend, Susanna. Morrow created the character of Raymond after meeting Kim Peek, a real-life savant; his characterization was based on both Peek and Bill Sackter, a good friend of Morrow who was the subject of Bill, an earlier film that Morrow wrote. Wikipedia
(Raymond doesn't want to go outside when it rains)
Charlie: Hey, Ray, you take a shower right?
Charlie: Well the rain is a lot like the shower, you get a little wet. What do you say, Ray? What do you say?
Raymond: Of course the shower is in the bathroom.
Charlie: That's the end of that conversation.