"Blasny, blasny."

That's all you need to know about "The Foreigner," the side-splitting comedy through Aug. 2 (with the same repertory cast for "Henry V," opening July 18) at the Pennsylvania Shakespeare Festival, Main Stage, Labuda Center for the Performing Arts, DeSales University, Center Valley.

Well, "Blasny, blasny," the phrase repeated by Jacob Dresch (Charlie Baker, "the foreigner" of the show's title), isn't actually all you need to know. For those not familiar with the Larry Shue play, we won't spoil the surprise.

Even for those who've seen the play, the PSF production has all the hallmarks of a definitive interpretation, with a detailed, lived-in looking set design by Bob Phillips, character-driven costumes by Marla Jurglanis, and lighting by Thom Weaver that creates, among other things, realistic vehicle headlights shining through windows.

Director Jim Helsinger keeps the action nimble and brisk with the actors talking in naturalistic southern accents (Jane Ridley is dialect coach). Helsinger's is a cast of contrasts, which works nicely with the play's amusing dialogue of probity and misappropriation.

We're introduced to Charlie Baker (Dresch evoking a frail, unassuming, emotionally-cauterized twentysomething growing in stature as the play unfolds) when he accompanies Sgt. "Froggy" LeSueur (Carl N. Wallnau) on a much needed vacation to a Georgia fishing lodge run by Betty Meek (Ridley, mining the emotions of an attentive, well-meaning, cheerful widow).

A young couple at the resort, Catherine Simms (Marnie Schulenburg with a fresh earnestness and sparkling demeanor) and the Rev. David Marshall Lee (Zack Robidas as a sincere, bespeckled yet fidgety individual), bring the love. Lee's increasingly odd behavior, especially in the shadow of his sidekick Owen Musser (Anthony Lawton), a county official who's, er, angling to take over the lodge.

Catherine becomes increasingly infatuated with Charlie who is "taught" English by the least likely of teachers, Catherine's younger brother, Ellard (David Button), who's, shall we say, a couple sandwiches short of a picnic.

"The Foreigner" is in the style of a Broadway stage drawing room farce where eccentric characters are tossed together like a salad, a tradition stretching back at least to George S. Kaufman's "You Can't Take It With You" (1936), but with a twist not unlike that of a good Agatha Christie whodunit caper.

The set is expansive and log-hewn, with an attention to detail, including a deer head above a stone fireplace, deer antler chandelier, spoon rack and quilt. It's decorated in early knick-knack. Glimpse the kitchen through a doorway and an entrance hallway beyond the main "great room."

The actors breathe life into the dialogue, which references Shakespeare ("He could turn a phrase."), Southern slang ("hoodoo talk"), pop references ("Klatu! Barada! Nikto!" from the 1951 science fiction film, "The Day The Earth Stood Still") and the contrast between "foreigners," i.e., immigrants, and residents of longer duration. The production crackles with energy, foreshadowing an explosive second act.

Wallnau has a jaunty stance and an even jauntier British accent.

His performance is nicely offset by the genuine menace created by Lawton in a performance that is riveting and truly chilling.

Dresch projects naive charm. He's a miniaturist of emotions. His interactions with Button and Schulenburg evoke the warm and fuzzy. What began as a nonentity becomes someone you root for.

The cast includes William Zielinski, Brian McCann and Wayne S. Turney.

Helsinger lets the story unfold naturally, and in an unassuming way, so that by the time of the second-act shocker, you are not ready for it. The contrast is effective, and necessary, as it gives the play its spine, without which it would be a mere trifle.

Fun "The Foreigner" is. Frivolous it is not. This clever, smart, play is as relevant, perhaps more so, than ever.

Tickets: pashakespeare.org, 610-282-WILL (9455)