inside interview, O’Brien recalls arguing in the writer’s room about the spelling of Homer’s famous ejaculate. O’Brien said that many members of staff wrote it “d’oh!” It is generally accepted today, although some writers spell it “doe”, which both O’Brien and Castellaneta consider to be risky. “A female deer,” Castellaneta jibes. Castellaneta, however, recalls first encountering the phenomenon in an early script – when “The Simpsons” was an animated segment on “The Tracy Ullman Show” – when it was written simply as voice directing. [annoyed grunt].
Indeed, it seems, even to this day, ‘d’oh! “Written in script as [annoyed grunt]. Groening has left Castellaneta what a [annoyed grunt] What will the sound be like? Castellaneta, delving into popular culture, remembers a popular character from the short film Laurel and Old Hardy played by comedian James Finlayson. Finlayson has a distinctive squeaky voice of his own, which Castellaneta imitates. It was a “d’oh”, but it was more like an angry “da– !,” interrupted by a silent pause, followed by an “oooh!” Castellaneta pointed out the “Da–” part, a way for the character to avoid saying “damn” on 1930s TV. Then, “D’oh” is a “damn” interrupted by an “Oh!”
O’Brien gleefully points out that saying “damn” on television doesn’t seem to matter anymore, as Castellaneta has just said publicly. Castellaneta urges a return with “F’oh!”
https://www.slashfilm.com/989621/homer-simpsons-famous-doh-catchphrase-has-a-surprising-unscripted-origin/ Homer Simpson’s famous D’oh catchphrase has an unexpected undescribed origin