When did “fun” become such a dirty word in classical music?

“Fun” attaches itself to kids’ or pops concerts, or a slapstick opera staging, long before it would get pinned on your average night at the symphony, if ever. (Not that those genres can’t be wicked smart, too.) But something strange, maybe dangerous, is happening if symphony orchestras, in their attempt to sum up the head-spinning spectrum of human life, swat away a few crucial emotions.

For a new vista on fun, run, don’t walk, to this weekend’s Chicago Symphony concerts, conducted by James Gaffigan. They’re exhilarating, life-affirming, ecstatic and erudite. Intermission was a parade of giddy smiles. I’m still wearing mine.

Thank Conrad Tao for that. The pianist, just 29, makes his CSO subscription debut with these concerts. After a dazzling, staggering Gershwin Piano Concerto in F on Thursday, that debut felt long overdue. Tao was born in Urbana in 1994; when his parents realized they had a multi-hyphenate prodigy on their hands (Tao composes prolifically, and for a time also played violin), the family moved to Naperville, in part so he could study at the Music Institute of Chicago. As he quipped before his encore, Tao was a CSO subscriber “from ages 5 to 9,” at which point he was off to Juilliard Pre-College in New York, where he’s lived since.

Based on Thursday’s performance and reception alone, CSO audiences will soon be like nagging parents, begging Tao for more homecomings. The Gershwin Concerto is too often overshadowed by its slightly older sibling, “Rhapsody in Blue,” and its many sutures are hard to reconcile. Depending on the interpreter, that’s the point.

But if you’ve shrugged at this concerto in the past, hear Tao on it. Like Gershwin, he knows a thing or two about bringing the music of the street into the concert hall: we’re talking about an artist whose repertoire includes not just the Three Bs but the Beach Boys and Beyoncé.

From Tao’s very first entrance, it was clear listeners were in the presence of a creative supernova: a syncopated sentence, a heartfelt echo thereof, then an accelerando that balled up his lines into an expressive tangle. Nor would you have been imagining it, had you heard some variation from the score: Tao inserted some improvisational embroidery in his cadenzas, so natural one might have missed it.

And those bizarro transitions? Under Tao’s fingers, they became places of joy and discovery. Two-thirds of the way through, at one point, the piano all but interrupts itself with a dainty ragtime number. Weird, right? Try funny: Tao ground the line to a halt before coyly introducing the rag.

And that was only the first movement. The applause afterward was so enthusiastic it briefly paused the concert.

Once the performance got going again, audiences were greeted with some of the best woodwind and brass work of the season so far to open the second movement — sweet and slow, like stretching drowsy limbs. (Spoiler alert: in a perfectly purist move, trumpeter Esteban Batallán uses a fedora to mute his schmaltzy solo, to awesome effect.) Tao carried his melodies masterfully, with elegant wrist rolls and big-eared engagement with the orchestra.

The only nitpick from this superlative debut: the Allegro agitato finale whizzed by too quickly to appreciate its motoric interplay between left and right hands. That’s what really gets this movement going, not sheer speed. Tao wanted to go several clicks faster than the tempo the orchestra laid out in its intro — so much so that his left-right vamping sounded almost like tremolos. It was a jaw-dropping display, if not quite satiating.

Tao’s final word on Thursday — his transcription of Art Tatum’s keyboard-spanning version “Somewhere Over the Rainbow” — was a better balance of face-melting virtuosity, profundity and invention. And it was so very Tao, layering his own fanciful tweaks atop Tatum’s fantasy. Worth the price of admission alone.

So were the Symphonic Dances from “West Side Story.” Sid Ramin and Irwin Kostal’s arrangement of Bernstein’s score gets the orchestra snapping and shouting. Even when you know it’s coming, it never fails to amuse. At the second cry of “Mambo!,” conductor Gaffigan turned around to call in the audience, who gleefully reciprocated. (All in all, it’s a banner program for unconventional orchestral techniques: violins and violas strum their instruments like guitars in the Gershwin’s Andante section.) Earlier, “Somewhere” delivered on its promise as one of the most soul-touching moments of the evening, gorgeous solos bundled together in a great sonic bouquet.

Next to the rest of the program, the concert’s shorter bookends got proportionally shorter ends of the stick. Samuel Barber’s “School for Scandal” Overture and Silvestre Revueltas’s “Sensemayá” — capaciously genius works in construction and orchestration — saw choppier ensembles and solos compared to the goods they sandwiched. Gaffigan’s interpretations of both felt closer to what you’d hear at an outdoor pops concert than a concert hall performance: plenty brilliant, but eliding some more nuanced emotional contrasts.

But as a podium technician, the guy’s a beacon. Gaffigan uses his whole body to conduct, and when it’s a program like this, that means hip-swinging, two-stepping and Bernstein-bouncing. His body language projected the evening’s many rhythms — often layered simultaneously — with clarion lucidity. He was also a genial colleague, wading through the orchestra to recognize solos (with the conspicuous omission of violist Weijing Michal, who deserves several rounds of applause for a lovely part in “Somewhere”). To goad Tao into venturing out for an encore, he crouched and whooped like a college football coach, leading the crowd in huge-hearted applause.

Anyhoo. Go, go, go to the symphony this week. You, too, might even have fun.

Program repeats 7:30 p.m. Oct. 20, 21 and 24, Symphony Center, 220 S. Michigan Ave.; tickets $35-250; cso.org

Hannah Edgar is a freelance critic.

The Rubin Institute for Music Criticism helps fund our classical music coverage. The Chicago Tribune maintains editorial control over assignments and content.