Tina Turner has better legs, and Mick Jagger's got more experience electrifying the crowds. Still, when it comes to singing septuagenarians, it's hard to top (what remains of) Monty Python as the Brit comedy troupe's surviving members reunite for a blissfully profane mix of their most popular songs and sketches. Doubling the 8,000-seat capacity of their 1982 Hollywood Bowl concert, the O2-set mega-show demonstrates the group's massive popular impact as fans who've memorized every word enthusiastically sing along, roaring with approval the instant they recognize each classic bit. Clearly, they're cult figures no more -- and everybody expects the Spanish Inquisition.

Dedicated to the late Graham Chapman, the evening opens with a newly animated segment in which the one-time King Arthur's head is punted off into the cosmos -- a deliciously irreverent touch, and yet a missed opportunity all the same. In theory, they could have rewritten the Marilyn Monroe sketch featured on the "Holy Grail" soundtrack, in which the dead actress' corpse is exhumed to appear in one last film. "But surely Miss Monroe was cremated?" asks an incredulous interviewer. Yes, agrees the director, but her cremated remains are always onscreen: in the ashtray, in the fire grate, in the vacuum cleaner.

"Monty Python Live (Mostly)" is more respectful than that -- but only just barely, as the "One Down, Five to Go" subtitle suggests. Though the show tries to forge on without Chapman, the sixth Python is sorely missed. Still, since they can't very well write his characters out of key sketches, that logistical challenge provides a rare opportunity for the ensemble's offscreen expat, Terry Gilliam, and its resident bombshell, Carol Cleveland, to expand their involvement with the group. Gilliam takes over Gumby flower-arranging duties, for example, while Cleveland has the honor of playing Chapman's stand-in during the "Spam" song.

It's remarkable how easily the rest of the gang manages to reprise their old roles, especially considering the vastly different paths each has taken in the 30-odd years since they last toured. These days, they don't need makeup to play the four old Yorkshiremen one-upping each other about the hardship of their respective youths, while the addition of facial hair makes their cross-dressing characters that much funnier.

With Python, the fourth wall has always been a porous barrier at best, and this show proves as self-aware as anything they've done. The instant the six cast members appear on stage, they soak up the arena's love, posing as the words "Photo Opportunity" flash on the screen behind them (not that the cameraphones ever go away). No subject is too sacred for satire, least of all their own egos. In the exploding penguin sketch, two mustachioed pepperpots tease poor Michael Palin for the travel docs that have kept him busy for the past quarter century.

Scaling the production to suit the enormous venue, director Eric Idle (the musical one) has expanded various songs to accommodate a company of 20 or so backup dancers, including a club-ready remix of "Nudge Nudge Wink Wink" that takes the routine to pervy new heights. At times, Terry Jones is clearly reading his lines (which many in the audience know by heart), and John Cleese -- who can scarcely keep a straight face at times -- clearly isn't as spry as he once was. In Cleese's case, rather than do without his "Ministry of Silly Walks," the show delegates it to the dancers, who deliver an imaginatively choreographed version of this most slapstick of Python pantomimes.

At their age, the costume changes aren't quite as brisk, though three jumbo screens keep the audience laughing during the downtime with reruns of Gilliam's best animations and other vintage sketches -- plus a couple new ones. Never once does the evening fall back on the series' trademark "and now for something completely different" catchphrase (a key precursor to such sketch shows as "Robot Chicken," which have honed bits to Vine length). Instead, Idle has gone to great lengths to weave a semi-logical flow between seemingly unrelated segments, Frankensteining thematically similar elements together to create the evening's program.

Just as earlier Python pics allowed them to get away with bits too bawdy for British broadcast standards, the stage format lends itself to some of the group's bluer material. Here, transgressions begin with the instrumental overture, which has the crowd singing "Sit on My Face" before the curtain comes up, and extend straight through to the tarted-up Busby Berkeley-style finale, "Christmas in Heaven," wherein the chorus girls' costumes have been altered to expose their breasts.

"The Penis Song" expands to include bonus vagina and bottom verses, while "Every Sperm Is Sacred" climaxes with two giant phallic cannons shooting bubbles out over the rows closest to the stage. It's not every day that you see an Oscar nominee passing loud and painful gas, barfing into his hat and sheepishly dumping its contents on his head, the way the good-sported Gilliam does in Chapman's stead, but that's the sort of shameless physical comedy Monty Python likes to mix with songs about philosophers and life's Big Questions.

As sacrilegious and politically incorrect as ever, the show features an elaborate version of "I Like Chinese" that might start a war if it were being sung for the first time and so many assaults on organized religion it's a wonder lightning doesn't strike the stage. Shudder to imagine what anyone who doesn't already know Monty Python's shtick might make of such a spectacle, which has been blown up to such garishly exaggerated levels that Baz Luhrmann would approve.

Who among these guys would have thought when they were spinning all this silliness 40 years ago that it might scale so well from the small screen to a venue as overwhelming as the O2? And yet, thanks to those giant video monitors and all the Python love under that dome, "The Lumberjack Song" feels as epic as "The Sound of Music," and that hotly-anticipated Spanish Inquisition sketch could rival the climax of "The Phantom of the Opera." While it would have been amazing to see more fresh material written for the occasion, this concert is something of a last hurrah for these legends, and in that regard, the only thing the show lacks -- apart from Chapman's ashes hidden in every scene, perhaps -- is 16,000 comfy chairs.

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