You can find lots of geezers sitting on park benches, but few as amusing and articulate as Nat (Charlie Riendeau) and Midge (Antonio “TJ” Johnson).

Nat and Midge meet on a Central Park bench, first involuntarily, later by design, and find themselves trading stories and discussing the state of the world – and their personal worlds – in a terrific production of Herb Gardner’s charming I’m Not Rappaport, playing through Sunday, Oct. 10, at Scripps Ranch Theatre. Robert May directs with a deft hand, staying out of the way of the story.

Nat, an old Jewish radical, reminisces about joining the Communist Party “and the human race” in 1919 and being on the front lines when workers won a 10% wage increase and the first 40-hour work week in the city.

Nat’s body may move more slowly than it once did, but his brain hasn’t slowed a bit. Now he spends his time spinning tales, taking on other identities (an urban lawyer, a Mafia don and “Dr. Friedrich Engels” are a few of them) and solving the world’s problems from the bench. His biggest personal problem is avoiding his daughter Clara (wonderfully played by Julie Anderson Sachs), who worries that her father’s grip on reality is loosening and wants to see him in a supervised setting.

African American Midge is hiding from the tenants’ committee of the building where he has spent 42 years tending the furnace. The building is going co-op and will install an automatic furnace; Midge hangs out in the park to avoid getting the word that he is no longer needed.

Various other characters flit through the piece, all magnificently played: young punk Gilley (Dylan Chouinard), who tries to extort protection money from both of the geezers; Danforth (Max Macke), chair of the tenants’ committee; and young artist Laurie (Catherine Dupont), pursued by The Cowboy (Reed Willard), a drug dealer with a southern accent who wants the money she owes him.

But engaging as most of these characters are (Laurie, an underwritten plot device, is the exception), I’m Not Rappaport is a buddy story about these two hugely dissimilar men confronting (and comforting) each other while fighting meddling relatives, infirmity, failing eyesight and a creeping sense of insignificance.

Riendeau and Johnson have the kind of chemistry that makes you wonder why they’ve never worked together. Riendeau’s irascible old liberal idealist plays right into Johnson’s earthbound working stiff; both (but Johnson in particular) make acting look natural, even easy.

Whether it’s Nat saying, “Who needs sight when we got vision?” or Midge bringing Danforth up short with this analysis: Problem is, you givin’ me bad guy news, tryin’ to look like a good guy doin’ it,” you can’t help loving these two.

I’m Not Rappaport plays through Saturday, Oct. 10, at Scripps Ranch Theatre (Legler Benbough Theatre, Alliant International University). Shows Friday and Saturday nights at 8 p.m. and Sundays at 2 p.m. For tickets, call 858-578-7728.

It must have seemed a good idea at the time. Given that celebrity activism has become a big, pervasive (and sometimes annoying) business, why not a spoof of the phenomenon?

But the best laid plans run up against one of the worst scripts in recent memory, and the result is comedic disaster in Blair Singer’s Matthew Modine Saves the Alpacas, playing through October 18 at the Geffen Playhouse in Los Angeles. John Rando directs, but may want to leave this one off his résumé.

It seems that fame has passed Modine by since he was a1980s A-lister for films like Full Metal Jacket and Married to the Mob. Tired of living in a Winnebago and subsisting on junk food, he begs help in resurrecting his career from hotshot publicist Whimberly North (Peri Gilpin), a pale copy of the PR whirlwind penned much better by Douglas Carter Beane in The Little Dog Laughed.

After North vetoes Modine’s original idea of adopting an African orphan, her flamboyantly gay assistant Jeffrey (French Stewart) suggests a great public relations ploy: saving the alpacas in a tiny Peruvian mountain village from extinction, where the fuzzy undersized llamas are for unknown reasons not reproducing.

In Chimborazo, Modine meets the local Three Stooges named Abraham (Edward Padilla), Angel (Reggie De Leon) and Santos Panchos (Mark Damon Espinoza) and sees the remaining three alpacas in the form of huge furry puppets.

How to get them to mate? Do you really care?

Modine’s boyish good looks can’t help him save this lumberingly bad script, but at least he looks good in that Frank Buck getup.

Stewart is double cast, also playing French United Nations official Pierre de Perrier Jouet, an amusing Inspector Clouseau knockoff who exhibits only a passing acquaintance with English pronunciation.

Gilpin (familiar to many as Roz on “Frasier”) looks great, thanks to Robert Blackman’s costume designs, but Singer has confused a hard edge with just plain crude lines which do neither Gilpin nor the character justice.

Give Modine and his colleagues props for gamely attempting this mess. The very capable cast gives its all, but the project is sunk by Singer’s fuzzy notion of comedy and lame dialogue.

Matthew Modine Saves the Alpacas plays through Sunday, Oct. 18, at the Geffen Playhouse in Los Angeles. Shows Tuesday through Saturday at 8 p.m.; Sunday at 7 p.m.; matinees Saturday at 3 and Sunday at 2 p.m. For tickets, call 310-208-5454 or Ticketmaster 800-745-3000.