macaroni (n.) Look up macaroni at Dictionary.com
"tube-shaped food made of dried wheaten paste" [Klein], 1590s, from southern Italian dialectal maccaroni (Italian maccheroni), plural of maccarone, name for a kind of pasty food, possibly from maccare "bruise, batter, crush," of unknown origin, or from late Greek makaria "food made from barley."

Used after c.1764 to mean "a fop, a dandy; typical of elegant young men" (as in "Yankee Doodle") because it was an exotic dish at a time when certain young men who had traveled the continent were affecting French and Italian fashions and accents. There is said to have been a Macaroni Club in Britain, which was the immediate source of this usage in English.