Put on your pirate gear–or just tuck a napkin around your chin.  The Isle of Eight Flags Shrimp Festival is currently underway with an all-day sidewalk sale in downtown Fernandina Beach.   The annual crustacean celebration kicks into high gear tonight with Shrimp Festival opening ceremonies, the Miss Shrimp Festival Pageant, a pirate invasion and fireworks.  Visitors will find plenty to do and plenty to eat  from 6 to 10:30 p.m. at the Amelia riverfront.  The fun continues Saturday and Sunday, including shrimp in every possible culinary incarnation, a kids entertainment area, educational exhibits, tours, arts and crafts and live music.  Admission to the street fair and entertainment is all free, but you’ll want to bring a few dollars to splurge on a shrimp feast.