“Stuck a feather in his hat and called it macaroni.” What does that even mean? As it turns out, a macaroni was an 18th century hipster.
The Grand Tour was a tradition among wealthy young men in the 18th century. It involved travelling around Europe and trying to become cosmopolitan. Sometimes they came back to England with a taste for pasta, high wigs, and little hats on top. Sometimes the wigs were so high that you had to put the hat on with a sword. They called themselves the “Macaroni club,” and they sound ridiculous.
The name came from their habit of describing anything cool as “macaroni.” Shoot, the dandy is sometimes described as a more masculine reaction to the macaroni. The dandy!
Back to Yankee Doodle. This lyric is supposed to describe someone naive enough to consider something as simple as a feather to be the height of fashion. Makes sense.