Actor Louis C.K. arrives at the Hollywood FX Summer Comedies Party in Los Angeles, California June 26, 2012. (GUS RUELAS/REUTERS)

Jason Mraz and Jennifer Hudson. Check.

Sufjan Stevens and Shania Twain. Sure.

Green Day frontman Billie Joe Armstrong? Yep, throw him in, too.

I’ve seen a high-end parade of pop stars perform at the Kennedy Center over the past decade, but I’ve never seen anyone get quite the raucous rock-star reception inside Foggy Bottom’s marble box as that of 45-year-old stand-up comic turned cable-TV king Louis C.K..

This is what it looks like to reach the mountaintop — your vocal cords playing to the packed room like power chords, deftly connecting with thousands of parka-and-hoodied fans born not only after the felling of Kennedy, but also (as the comic noted to great effect) the downfall of Nixon.

Judging by the first of his two sellout sets Friday night, this is how it goes for a veteran Emmy-winning comedian and writer in total and winning control:

You go intellectual, and the audience members laugh.

You go psychological, and the collective sound builds to a howl.

You go scatological — riffing about bodily organs with the Concert Hall’s new pipe organ as your elegant backdrop — and the crowd’s respiratory surrender begins to verge on weeping.

Even when graphically describing his own middle-aged incontinence, Louis C.K. has already plotted his masterful pivot from literal low-end humor to higher-end social satire. It’s like moving from dysentery to dissenting commentary with the easy command of a champion. It’s punch-lining as sweet science.

As they say on the stage, Louis C.K. killed it Friday night. Or perhaps more accurately, killed them.

Old ladies. Dogs. His daughter’s fish. Children with nut allergies. Under his scathing comedic scalpel, all the patients die — so that we may laugh in lively fashion from a vicariously delicious distance.

As the Boston-bred comic himself joked with a glimmer of amazement, he was sometimes working blue “inside a national monument.”

Louis C.K. also worked in blue, naturally — taking the stage in a variation on his standard uniform: simple navy shirt (the comic went “formal,” going with the polo instead of the T), standard-issue Levi’s and chunky black shoes.

Dressing down, of course, has become de rigueur when you’re the hottest comic working today — as he’s widely acknowledged to be. In a previous century, each reigning comedian (from Seinfeld to Stewart to Rock) was dressed up, be it in swaggering jackets or sweaters paired with that acid-wash. As the torch has passed from Chappelle to C.K. (with middleman Lewis Black wearing only a leash of a tie for comic effect), we not only get the comedians we deserve. We also get the stage attire that reflects our times like an economic indicator.

And as Louis C.K. kidded, this was he looking his best, scrubbed up for the spotlight at the lofty Kennedy Center, wearing clothes that collectively cost only a few bucks.

The schlubby threads only heighten his entire comic persona, though.

Whether onstage or in character for his hit FX show, “Louie,” Louis C.K. proudly stands for gradual dissipation and dissolution. This is Man in Blissful Decline.

Whether writing for Conan or working the road, Louis C.K. has been practicing his craft for decades. But it was only once he had kids — and began incorporating their presence into his act — that he gained traction toward stardom. (One turning point: His genius bit about a perpetually questioning child, shorthanded by the title “Why?”)

As Louis C.K. became a father, his “declining” physical presence (his red hair thinning, as if undergoing a continental drift toward a strawberry-and-gray goatee; plus adding a few “parent pounds”) began to become the perfect supporting player for his comic persona. As Louis C.K. ingeniously knows, nothing backs a brilliant comic riff like a midriff that says: “[Expletive] it — I’m giving up!”

Louis C.K.’s facial effects have also morphed into comedic perfection: First he gives you the deviously dancing eyebrows, then a glint in the eye, then the punch line is followed a half beat by an infectiously wide smile that effectually says: “I may have just crossed a line — but you just crossed it with me.”

The comedian was typically self-effacing about his body Friday, acting out how putting on his socks — “folding like a bowling ball” to do so — is the worst part of his day, no matter what follows. But Louis C.K. also knows the ultimate twist on this joke: He’s never felt better about his life.

“I’m 45!” he beamed to the audience, speaking to the crowd, predominantly 20- and 30-somethings, like a wise figure from their future.

“A 55-year-old garbageman,” he faux-lectured about age and experience, “is smarter than a 28-year-old triple-PhD. . . . He’s lived a life.”

Louis C.K. is divorced. He is in semi-physical decline. And between body-part jokes, he speaks from the great wisdom of experience.

Even on that mountaintop, he’s smart enough to whisper close in the ear of his fandom:

“I’m 45! It gets better!”

In Louis C.K.’s case, comedically, it certainly does.