In fact, the word “dude” is thought to have originally been a shortening of “Yankee Doodle.” In the original, British-penned lyrics of the song, which were written to poke fun at American troops during the French and Indian War, you’ll note that Yankee Doodle is described as a dandy who is a fabulous dancer and wears a dashing feather in his cap. The term doodle is thought to be from a German word meaning “fool” or “simpleton” (though this sense is unrelated to that seen in “labradoodle” and the like, which is a rebracketing from “poodle”).
Thus, “dude” wasn’t exactly a flattering term in its early years.