What do parents do when they’ve packed the kids off to school? They fool around, yes, but Billy Aronson’s sophisticated sex farce never loses its grasp on reality, and a first-rate cast of comic actors expertly builds a sense of cumulative ridiculousness.

The First Day of School. By Billy Aronson; Pete Pryor directed. Produced by 1812 Productions through October 25, 2009 at Plays and Players, 1724 Delancey Pl. (215) 592-9560 or www.1812productions.org.

Sex and the married parent

Right off the bat, Billy Aronson’s The First Day of School delivers an original perception: Today’s hovering “helicopter parents” feel so traumatized about sending their kids to school that many of them take the entire first day off from work or chores, lest any contingencies arise. Once they’ve assured themselves— usually in the first five minutes— that their kids are safely ensconced with old schoolmates and an amenable teacher, the parents find themselves with unexpected time on their hands.

What to do? David (Pete Pryor) and his wife Susan (Karen Peakes) ponder their options: They could visit the Art Museum… go to a movie…. or “We could try having sex with other people,” David suggests brightly.

With that, we are off on a rollicking sex farce in which David and Susan attempt to seduce their similarly idle fellow parents. The underlying gag here is that David and Susan are neither squeamish nor secretive about their proposed activity, but everyone they approach assumes they must be. When David and Susan ask, “So would you like to have sex with me?” in the middle of a conversation about schoolteachers, they do so as if they’re arranging a play date for their kids.

Beyond Shakespeare

To some extent David and Susan function like Alice in Wonderland here: They’re an ordinary couple making an outlandish proposition to three outlandish characters who are desperately trying to pretend they’re ordinary. In each case the proposed seduction triggers a long and hilarious monologue that takes Shakespeare’s “Methinks the lady doth protest too much” to extremes the Bard never imagined.

When Susan offers herself to the awkward Peter (Chris Faith), he rejects her immediately but refuses to drop the subject, rambling on for five minutes about his refusal to betray his wife and children, even if they never found out. (“Kids are sensitive. They can sense things.”) Kim (Susan Riley Stevens), a coiffed career woman wrapped tightly in a color-coordinated tweed dress and heels (think Libby Dole), denounces David for his effrontery, but she can’t drop the subject either. “I’m sorry,” she lectures David, “but men are just hard-wired different from women…I channel my desires to make me a stronger person… I jog all the time!” Alice (Jennifer Childs) is a business-suited lawyer who fantasizes sexual overtures from every man who so much as brushes against her.

Updike with humor

All this sex talk inevitably leads to action, but Aronson’s script consistently eschews the obvious and remains a step ahead of the audience, allowing a cast of very talented comic actors to build their own sense of cumulative sexual ridiculousness— sort of like a John Updike novel, if only Updike had a sense of humor.

Faith, Stevens and Childs make the most of their juicy roles; Stevens’s simulation of the orgasm that Kim absolutely refuses to have with David is subtler and consequently much funnier than Meg Ryan’s famous scene in When Harry Met Sally. But Pryor (who directed) and Peakes deserve much credit as well for the restraint with which they serve as respectable foils for their would-be targets.

A trio with cell phones

Not the least of this comedy’s sophisticated charms is its consistent grounding in reality (unlike, say, the smarmy theatrical sex gags of The Producers or Dirty Rotten Scoundrels). Unlike so many playwrights, who spend their time hanging around actors and theaters, Williamson has clearly marinated himself in the world of real parents, children and adolescents. One of the play’s most inventive moments occurs when the three potential seducees conduct simultaneous cell phone conversations with their respective spouses, interspersing fragments of the very one-sided dialogues we’ve all heard countless times from cell-phone parents on sidewalks or Amtrak trains (“It’s too late for ice cream— it’s almost dinner”).

An epilogue scene, set five years after the original action, is quite pointed and funny as well but would have benefited from an intermission. But this is a minor quibble. For the most part, The First Day of School is a combination of a first-rate script performed by first-rate comic actors, expertly coordinated.