It's time for another dysfunctional Christmas in Tuna, Tex. Young Stanley Bumiller is still in rehearsals for "A Christmas Carol," the play he is required to perform to satisfy his court-imposed community service. Didi Snavely, proprietress of Didi's Used Weapons, is trimming the tree again, with live grenades, no less. And Stanley's mother, Bertha, decked out in her festive best -- poinsettia earrings and pine-green polyester pantsuit -- is back at the kitchen table, bitter over the protracted absence of her wayward ex-con of a husband.

"Your father promised not to miss another Christmas," she says. "Hitler promised to stop after Czechoslovakia."

So it goes in squalid little Tuna, third-smallest burg in all of Texas and the ditsy playground for Joe Sears and Jaston Williams, who between them play 22 florid characters in "A Tuna Christmas," their affectionate, funny and finely observed sendup of back-porch life in the hick-infested towns of the rural South.

"A Tuna Christmas," like the other pieces of the Tuna trilogy, "Greater Tuna" and "Red, White and Tuna," has played here before; on this occasion, it runs through Sunday at the Warner Theatre. And even as a first-time visitor to Tuna and the gallery of oddballs Sears and Williams so wittily put on display, I can imagine a return trip might prove as beneficial to the funny bone as the initial treatment.

This is not an original notion. Clearly, many Washington theatergoers are on intimate terms with the band of outrageous souls who inhabit Tuna; at the show I attended, entrance applause greeted perennial favorites like Didi, Williams's take on a burned-out gun nut, and Bertha, Sears's impersonation of a repressed small-town housewife who finds solace in bundt cakes, stolen nips of brandy and fervent participation in the local Smut Snatchers club.

Sears and Williams, under the direction of Ed Howard, have been at this a long time now -- they've been touring their "Tuna" shows for 20 years -- and they've polished their Spoon River Anthology-meets-the-Alamo shtick to a high gloss. What distinguishes this crowd-pleasing evening from others that feed so ravenously on caricature is the warmth and respect these actors seem to harbor for their creations. It would be easy to turn the inhabitants of mythical Tuna into mere buffoons, but the "Tuna" men never patronize them or us. There is no mugging here, no pandering to the city they're visiting; the closest they come to a Washington joke is when Didi barks at a slow-moving underling, "Don't just stand there like a government employee!" Which does of course get a big laugh at the Warner.

"A Tuna Christmas" is in the great comic tradition of poking gentle -- and occasionally lacerating -- fun at American innocence. Christopher Guest does this frequently in his mockumentary movies; Tuna, Tex., is sort of a kissing cousin to Blaine, Mo., the fictional stoolmaking capital of the world in the hilarious "Waiting for Guffman," Guest's spoof of the grasping types who populate community theater. The enjoyment of both "Tuna" and "Guffman" is in the penetrating moments that capture an exquisite detail of life as it is lived, as when Sears, playing the voluminous Bertha in a dark bouffant, delicately flutters his fingers, swatting away both the cake crumbs and the character's anxieties.

The lineage of these bumpkins goes back to Shakespeare; you might even cast a handful of the Tuna denizens as the "rude mechanicals" in a Lone Star updating of "A Midsummer Night's Dream." (The "Tuna" guys are no slouches in the History of Drama department; they pepper the show with references to plays and musicals, from "Medea" to "South Pacific.") Some of the characters, admittedly, are broader than others. Williams, excellent in the male roles, has a tendency to push it a little too ostentatiously in some of the female ones. His Arles Struvie, lonely-guy deejay at radio station OKKK, is a more satisfying character than his Vera Carp, the town's fussy, bourgeois showoff (although Vera's mangling of Spanish in front of her maid, Lupe -- pronounced here as "Loopy" -- is a treat).

Then again, Sears is such a natural playing the hefty homemakers and dowagers of Tuna that any stage partner might be hard-pressed to seem as authentic. It's hard to imagine having your fill of his Bertha (or Aunt Pearl or the suggestively named Inita Goodwin). Bertha is the deluded spirit at the heart of "A Tuna Christmas"; shackled to a humdrum existence centered on her warring twins (both nicely played by Williams) and the vain conviction that her errant husband will come home, she fills her empty days with silly and even dangerous distractions, like the Smut Snatchers, who believe that even "Silent Night" has to be censored.

In Sears's hands, Bertha has the virtue of being redeemable. The love of a good man would have changed everything for her, as Sears and Williams (and their co-author Howard) suggest in the endearing final scene when, at the radio station, Arles makes a play for her. Such is Sears's gift that the slightest whiff of sexuality comes to the fore, and you find yourself rooting for an unlikely assignation.

"A Tuna Christmas" has its quota of more biting satire. The gags at the expense of the Klan are sharp and incisive, and the one-horse-town fascination with firearms is lampooned brilliantly in Didi's shop: "Weaponry for the car, the home, the workplace." The only aspect of the production that betrays the freshness of the material is the age of Loren Sherman's set, which is designed to look like a rendering of the Old West in a pop-up book. The seams in the back wall are frayed to the point of shabbiness. It's time to call in a handyman.

Otherwise, "A Tuna Christmas" holds up remarkably well. Even a dyed-in-the-wool Yankee can find joy this far south of the Mason-Dixon line.

A Tuna Christmas, by Jaston Williams, Joe Sears and Ed Howard. Directed by Ed Howard. Sets, Loren Sherman; costumes, Linda Fisher; lighting, Root Choyce. Approximately 2 hours 10 minutes. Through Sunday at the Warner Theatre, 13th Street between E and F streets NW. Call 202-432-SEAT or visit www.ticketmaster.com

Bertha and Stanley Bumiller as channeled by Joe Sears and Jaston Williams in the seasonal favorite, playing through Sunday at the Warner Theatre.Joe Sears and Jaston Williams are the men of a thousand faces (or 22, at least) in "A Tuna Christmas."