What keeps the "Tuna" franchise fresh must be meanness, the seemingly bottomless reservoir of spite and self-regard among the yokels of fictional Tuna, Tex., that generates two hours' worth of zingy, twangy one-liners. Meanness, that's it -- that and two guys making quick changes from jeans to leisure suits to dresses.

"Red, White and Tuna," now at the Kennedy Center's Eisenhower Theater, is the most recent of the three "Tuna" shows concocted by Joe Sears and Jaston Williams with director Ed Howard. It's been here before -- Sears and Williams seem to cruise through town in one "Tuna" vehicle or another every year or two -- and it still has its ornery, laid-back appeal.

The show doesn't bother much with plot. Sears and Williams are content to play about a dozen characters each, most of whom are chewing on some sort of anger or resentment, and all of whom are deft at delivering a tart Texas punch line. Take Didi Snavely (Williams), a hard-as-nails gun shop owner in a skirt and plastic raincoat, who explains how the Americans defeated the Brits during the Revolution:

"They won it," drawls Williams in Didi's cigarette-scorched baritone voice, "because they shot 'em."

Williams is the wiry one; his gallery of characters ranges from relaxed ol' radio deejay Arles Struvie to vivacious waitress/caterer Helen Bedd and the wound-up Vera Carp, who has lately been cleaning up the lyrics of Bible songs. Williams also plays (meekly, of course) animal rights activist Petey Fisk, who is protesting the local Critter, Varmint and Pest Fest by holing up with a box of scorpions to prove that all animals are our friends. For reasons that don't have to do with the scorpions alone, that optimistic attitude just doesn't last long in Tuna.

The stocky Sears plays his male characters with skill. Witness the otherworldly calm he brings to R.R. Snavely, Didi's husband, who's just back from a few years on a UFO, or the comic hissy fit he throws as the flamboyant theater director Joe Bob Lipsey.

But Sears is nothing short of magic in a dress, or in a lime-green polyester pantsuit: He surely holds the patent on chicken-fried drag. There is undeniable cow-town majesty in the carriage of his Pearl Burras, a portly matron in a bold floral-print dress that makes her look like a walking garden. (Linda Fisher's costumes get credit for wit and ingenuity, especially given the multitude of quick changes.) And Bertha Bumiller, the one in that pantsuit, is the richest character in the show. Sears puts impressive maternal wrath into Bertha's threat to "smack the snot" out of one of her two grown children -- as retribution for unchristian behavior -- yet he's delightfully coy and tender as Bertha and Arles see if they can keep their engagement on track. It's a marvel that Sears somehow seems to grow larger and more physically serene in women's wear.

That physical serenity is actually one of the hallmarks of the whole show. Sears and Williams stroll around so slowly that you figure Tuna has no clocks; they don't rush anything, and they don't push their material. And that's really why the "Tuna" shows continue to work: They are performed by a pair of unflappable pros.

Red, White and Tuna, by Jaston Williams, Joe Sears and Ed Howard. Directed by Ed Howard. Settings, Kevin Rupnik; lighting, Root Choyce. Approximately 2 hours 10 minutes. Through July 10 at the Kennedy Center Eisenhower Theater. Call 202-467-4600 or visit www.kennedy-center.org.

Jaston Williams and Joe Sears have grown in their multiple-denizen roles in "Red, White and Tuna."Joe Sears and Jaston Williams as two of the dozen or so characters each takes on in "Red, White and Tuna."