By Jean Lowerison

You know the King Arthur legend. You’ve probably seen Lerner and Loewe’s musical “Camelot.”

And then there’s “Monty Python’s Spamalot.”

Unlike anything else — including history or legend — “Spamalot” is Eric Idle’s gloriously goofy spoof of the Knights of the Round Table, based on the famed comedy group’s 1975 film “Monty Python and the Holy Grail.” Idle wrote the book and lyrics and co-wrote the music with John Du Prez. The show is a total hoot and has already been extended through Aug. 12 at Cygnet Theatre.

“Spamalot” opens with a historian (Bryan Banville) telling the audience we’re in England in 932 A.D. The stage is soon crowded with a hopelessly colorful bunch of clearly un-English peasants — some don long blond braids, some wave Finnish flags, and others carry fish of varying sizes for the “Fisch Schlapping Dance.”

When the historian wails “I said ENGLAND,” the scene shifts to Cygnet’s artistic director Sean Murray as King Arthur, “riding” in with sidekick and “steed” Patsy (Jonathan Sangster), who knocks two coconut shells together to provide the sound of horse hooves. Murray is reprising the role he performed splendidly a few years ago at Vista’s Moonlight Amphitheatre.

Arthur is looking for recruits for his Knights of the Round Table. In this goofy, fact-challenged retelling of the story, he’ll find a few — and even get heavenly instructions for a quest.

There’s Dennis (David S. Humphrey), who lives with his mom Mrs. Galahad (Anthony Methvin). Dennis challenges the very idea of the divine right of kings, especially Arthur’s claim that the Lady of the Lake handed him the sword Excalibur and “that is why I am your king.”

Dennis maintains that “supreme executive power derives from a mandate from the masses, not from some farcical aquatic ceremony.” But he agrees to go along if Arthur can prove that “the soggy old blonde exists.”

She does, played and sung smashingly by Christine Hewitt, surrounded by her barely-clad Laker Girls who can sing, dance, and even perform a cheerleading routine complete with pom-poms. So Dennis is dubbed Sir Galahad.

Then there’s Lancelot (Evan White), hopelessly blond and foolishly fearless, who will discover his true love when asked to save a “maiden” in distress.

That would be Prince Herbert (Banville), who doesn’t want to marry the girl chosen by his dad just because her father owns a lot of land.

God (uncredited) will also appear on video, giving the Knights a quest: to find the Holy Grail, a chalice allegedly used at the Last Supper. “Get to it, all right?” he says. “These people don’t have all night.”

But the English knights will encounter the extremely inhospitable French army, most especially the rude French Taunter (Banville), who will force the English to withdraw and run away. Banville gets a workout in this show. The actor also plays Not Dead Fred, who insists he is not a plague victim — no matter how hard they try to bury him.

It goes on like that, offering tap-dancing knights, a killer rabbit, and a monk who sees that the Black Knight (Humphrey) has lost his arms in battle and picks up arms for the poor.

Silly? You bet. Groaners? Sometimes. But funny? Absolutely — and full of references to movies, actors, and even to Broadway theater itself, asserting in a hilarious song that “You Won’t Succeed on Broadway” (if you haven’t any Jews).

The costumes are uncredited but terrific and numerous. Sarah Palmer Marion is listed as costume coordinator and dresser — the latter a huge job and well done.

Sean Fanning’s surprisingly simple set features an expanse of blue sky with huge clouds. Animated sheep, buglers and such scurry across or dive down through the clouds during the overture.

Matt Lescault-Wood’s sound and Chris Rynne’s lighting are excellent. Blake McCarty contributes a plethora of projections; Murray said part of the downsizing required to put this big show in Cygnet’s small space required lots of animation.

Kudos also to music director Terry O’Donnell’s small but mighty six-member band.

And Katie Banville’s choreography is lively and great fun to watch.

With a terrific cast, fine direction and many laughs, “Monty Python’s Spamalot” is great summer fare. Don’t miss it.

—Jean Lowerison is a long-standing member of the San Diego Theatre Critics Circle and can be reached at infodame@cox.net.