Irresistible pop culture pirates predate Johnny Depp’s Jack Sparrow by more than a century. W.S. Gilbert and Arthur Sullivan’s enduring comic opera “The Pirates of Penzance” debuted in 1879, and it’s in no danger of fading from the stage.Two different productions open in Louisville this season. The first, produced by Metro Parks, opens Thursday. It's part of the Iroquois Amphitheatre’s 75th anniversary year. (Chicago's The Hypocrites bring their version to Actors Theatre of Louisville in January.)"They're such a lot of fun to do," says director Greg Maupin. "I'm a big fan of Vaudeville and music hall and that sort of thing." The lighthearted romantic comedy follows the ups and downs of Frederic, the loyal apprentice to a band of sweet-natured pirates who falls in love with Mabel, a daughter of a modern major-general.When she and her sisters encounter the band of pirates and nearly end up married off to the whole band, they're saved by her father who claims to be an orphan (the pirates are very soft-hearted toward orphans). Frederic's 21, so his apprenticeship is up, but wait -- he was born on a leap year! And so he nearly misses his opportunity to marry his beloved, but then the cops show up and the pirates' loyalty to the Queen is tested and oh, the plot is pretty silly, really. But no matter.Though many of Gilbert and Sullivan’s operettas became successes in the United States, “The Pirates of Penzance” was the only one to premiere on this side of the Atlantic. Maupin, who also sings the role of the Pirate King, says the music is the key to Gilbert and Sullivan’s popularity. “Victorian stage comedies with light elements of social satire probably would be dead completely were they not set to really remarkably catchy music, really cruel earworms,” says Maupin. Take the rapid-fire tongue-twister "I Am the Very Model of a Modern Major-General," which boasts one of the best annotated Wikipedia pages of all time. If you can't quite memorize that many words, the production will project the sing-along choruses on stage and include a QR code in the program so audience members can access the full libretto. “These were big pop tunes at the time. These were popular. You sang them around the piano at home. People took solo versions out and did salon and music hall and vaudeville performances of them. That melding really became American musical theater,” Maupin says."The Pirates of Penzance" runs August 8-17 at the Iroquois Amphitheatre.