MORE ON BOSTONIANS' USE OF THE WORD "RETARDED"From
Michael Feldman, Boston University professor who teaches a class on informal English:
It seems clear that "retarded" as a substitute for "stupid" evolved from a childhood insult among baby boomers into a general pejorative adjective at the same time it became politically incorrect to use it as a descriptor for the mentally challenged. It is also interesting to note that while "retarded" became commonly applied to anything not up to snuff (movies, music, jobs, clothes), the adjective it replaced, "stupid" was being converted into an APPROBATORY adjective in "hip-hop" slang, so that stupid and retarded became slang antonyms!