Stuck a feather in his cap....
I found out what "Macaroni" means in the song Yankee Doodle!
A "Macaroni" in the period of king George (of tea taxing fame)
was an excessively stylish gentleman. Those who aspired to
high fashion (and succeeded) were a Macaroni.
I suspect that the point of Yankee Doodle was that he aspired
to high fashion... and failed. ;-)