Where the heck did the word “duh” come from?
The OED traces it back to 1943, to a Merry Melodies cartoon of all things! It also calls its etymology “imitative,” which makes sense to me; it duplicates the sound of a half-wit’s comical slowness.
peepthis nailed it.
You might be interested in the quote from the cartoon:
And the usage of the word “duh” used as a retort to mean “that is exceedingly obvious”(thanks to J.E. Lighter for the quote and definition), is attested to as early as 1963.
I wouldn’t have guessed it that early.
Also pronounced “der” and “doy.” During the 1980s, I heard the latter used in the form of “No doy,” a grade-school version of “No shit, sherlock.”