It seems like everyone dresses up in A Confederacy of Dunces. Officer Mancuso is forced by his sergeant to wear a series of ridiculous undercover outfits—a fake beard, a beatnik outfit, a Santa Claus suit, to name a few—and Dorian Greene's friend, Timmy, dresses in a sailor suit, while other folks at Dorian's party put on costumes as well. Darlene dresses up as a Southern Belle for her striptease act; Lana Lee dresses up (okay, more like down) as a teacher for her nude photographs. And, of course, Ignatius has his pirate costume, with the plastic sabre and earring.
The costumes in the novel are almost never meant to fool anyone, though. Mancuso's "undercover" outfits don't deceive anyone except Lana Lee at the very end of the book, for instance, and they are intended to humiliate rather than conceal him.
The Mardi Gras of Bird Dung
Instead, dressing up in this book seems to be in the spirit of Mardi Gras, New Orleans's famous pre-Easter carnival. To dress up is fun, and funny, and a little nuts; it's a sign of a world where everything is heightened and more than a little crazed. Not sure about you guys, but we actually dressed as Ignatius himself while reading the book, complete with green earflaps and a parrot on our heads, and thus discovered that it is difficult to read a book spattered with cockatoo poop.
Interestingly enough, a statue of Ignatius Reilly was erected in New Orleans. Like, for real and in our world. It stands in front of what used to be the D.H. Holmes department store—except once a year at Mardi Gras, when it has to be moved to make way for the party. As such, it's almost as if the carnival and the statue are substitutes for each other. Ignatius is the Mardi Gras for New Orleans when Mardi Gras isn't in season. We're thinking John Kennedy Toole would appreciate that.