The purple, green, and gold sugar decorations on a Mardi Gras king cake symbolize power, faith, and justice. A king cake is a tradition with roots in Catholicism. And is enjoyed on the Epiphany, or Twelfth Night (the 12th day of Christmas when the magi bestowed gifts on the newborn Christ). Many Catholic and Christian cultures observe King's Day. However, in New Orleans, the day kicks off the Mardi Gras season, which culminates on Fat Tuesday, the day before Ash Wednesday.