The Pirates of Penzance was the only Gilbert and Sullivan opera to have its official premiere in America: The pair staged it in New York City on New Year’s Eve in 1879 in hopes of securing U.S. copyright protection and preventing unauthorized productions. But it didn’t work, and as had happened with the Brits’ previous hit, H.M.S. Pinafore, scores of knockoffs played across the States, often taking great liberties with the libretto and orchestration (and, of course, failing to generate royalties for the show’s creators). It’s safe to say that they probably didn’t improve on the original. But the liberties taken in the adaptation from award-winning Chicago troupe the Hypocrites have quite different results: a night of Victorian opera that somehow manages to delight squirmy small children, sundry hipsters, and graying Cantabrigians alike.

Playing at the American Repertory Theater through June 2, the Hypocrites’ fun and fizzy Pirates of Penzance transforms the Loeb Drama Center into a wonderland of beachy-keen kitsch, complete with tiki lights and a grass-hut bar churning frozen drinks. Traditional seating is available, but brave souls should opt for the onstage Promenade, where you may perch at a picnic bench, on a plastic cooler, inside a kiddie pool alongside assorted rubber duckies, or on the floor (though be forewarned: you may inadvertently get a glimpse up a pirate’s short-shorts). Wherever you sit, don’t get too comfy. The action unfolds all around you, and a bathing beauty or Major General will likely need to be in your spot at some point during the show. Cast members gesture or tap you on the shoulder to let you know it’s time to scoot, which works out fairly smoothly, considering all the piratical hijinks afoot — there was only one drink-spilling collision during my viewing.

Running 80 minutes — with a whopping one-minute intermission — the show sails along at a brisk pace, and the beach-party shtick feels weirdly pitch-perfect instead of gimmicky, perhaps in part because Gilbert and Sullivan’s plot is already so goofy. Our hero is Frederic, who was mistakenly apprenticed to a band of a tender-hearted pirates (who spare all those who claim to be orphans). Frederic loves his mates, but is such a goody-goody “slave of duty” that he feels compelled to help the police bring his former crew to justice once his employment ends at age 21. He also falls for the banjo-plucking Mabel, after realizing that the crew’s maid, Ruth — the spectacled, curler-headed, accordion-playing old biddy who’s the only female he’s seen since childhood — isn’t the paragon of beauty she’s led him to believe. (In a clever move, the fabulous Christine Stulik plays both Ruth and Mabel.) But Frederic’s plans are derailed when he’s told that his leap-day birth means his term of service technically extends until his 21st birthday — when he’ll be 84.

The hyper-kinetic cast spit out polysyllabic rhymes, sing, dance, and play a panoply of instruments — ukulele, clarinet, harmonica, guitar, banjo, xylophone, washboard, finger cymbals, even a saw — often all at once, weaving in running jokes and eliciting laughs with something as simple as a trilled syllable or a well-timed stomp. All in all, it goes down as easy as those tropical cocktails from the grass hut, sans hangover.

Pirates of Penzance plays at the A.R.T.’s Loeb Drama Center through June 2. Find tickets and more information here.