A New Orleans institution. Super Sunday is the official day the Mardi Gras Indians unveil their new costumes for the Carnival season. Mardi Gras Indians are mostly African-American Carnival revelers in who dress up for Mardi Gras in costumes influenced by Native American ceremonial apparel. The costumes are extremely intricate and take much of the year to complete; starting right after one mardi gras for the following carnival.