Duuuuuude ...

Feeding those etymologists among us is the latest research from a Univ. of Pittsburgh linguist, an exposition of the word "dude":

Kiesling says in the fall edition of American Speech that the word derives its power from something he calls cool solidarity -- an effortless kinship that's not too intimate.
[...]
Historically, dude originally meant "old rags" -- a "dudesman" was a scarecrow. In the late 1800s, a "dude" was akin to a "dandy," a meticulously dressed man, especially out West. It became "cool" in the 1930s and 1940s, according to Kiesling. Dude began its rise in the teenage lexicon with the 1981 movie "Fast Times at Ridgemont High."