Wikipedia
"D'oh!" is a catchphrase used by the fictional character Homer Simpson, from the long-running American animated sitcom The Simpsons (1989–present). It is typically used when Homer injures himself, realizes that he has done something stupid, or when something bad has happened or is about to happen to him. All his prominent blood relations—son Bart, daughters Lisa and Maggie, his father, his mother and half-brother—have also been heard to use it themselves in similar circumstances. On a few occasions Homer's wife Marge and even non-related characters such as Mr. Burns and Sideshow Bob have also used this phrase.
In 2006, "d'oh!" was listed as number six on TV Land's list of the 100 greatest television catchphrases. The spoken word "d'oh" is a sound trademark of 20th Century Fox. Since 2001, the word "doh" has appeared in the Oxford English Dictionary, without the apostrophe. Early recorded usages of the sound "d'oh" are in numerous episodes of the BBC radio series It's That Man Again between 1945 and 1949, but the OxfordWords blog notes "Homer was responsible for popularizing it as an exclamation of frustration."