The gods have a wicked sense of humor.

You can almost hear their guffaws as they match Jo (Rachael VanWormer), a sex-crazed young woman who hates babies, and Jules (Steven Lone), a geeky socially-challenged gay scientist, via a Craigslist ad for “intensely significant coupling.”

Even better: they meet in his subterranean university research lab, minutes before a direct comet hit destroys everybody aboveground.

That’s the premise of Peter Sinn Nachtrieb’s quirky 2008 boom, running through Sunday, Jan. 31, at San Diego Repertory Theatre. Sam Newhouse directs.

Jo, you see, is a journalism student with an assignment: “Find a story in an unconventional place that uplifts you. Personally. Deeply. Truly.” She has decided to write about “random sex as the last glimmer of hope in a decaying society.” She’s answered Jules’ ad offering to “have sex to change the course of the world” hoping to have some great no-strings humping. And brought plenty of notebooks to document it.

Jules has spent years in his underground bunker studying the sleeping activity of fish – the Beaugregory Damsel Fish like those swimming around in his aquarium, to be exact.

His studies and the mathematical calculations on a large bulletin board have led him to expect a cosmic cataclysm; he placed the ad because “the future of humanity depends on it.”

It’s a post-apocalyptic Adam and Eve story that has these two oddballs talking (and moving) around and over each other with lots of collisions but very little connection. In fact, they spend most of their time bickering – not usually a joy to watch, but Nachtrieb’s clever dialog makes this halting mating dance utterly engaging, albeit profane.

But there’s a third character in boom. She is Barbara (Sylvia M’Lafi Thompson), docent in a natural history museum, describing the action from sometime in the future. From her own control station above Jules’ lab, she pushes levers, switches and knobs, provides percussion accompaniment to the proceedings below and occasionally descends to explain things, including a particularly fanciful account of her own conception.

This is a wonderfully engaging, oddball comedy, boasting a terrific set by David Lee Cuthbert, fine tech work, excellent direction and spot-on acting.

VanWormer has played many a quirky character. The bright but grouchy Jo is right up her alley, and she cashes in with a no-holds-barred performance that makes Lone’s geeky, committed scientist that much better ... and funnier.

And Thompson, who never fails to impress, is terrific as the third-wheel observer.

It comes as no surprise that boom is the most-produced new American play this season, counting some 14 productions.

Will this mismatched pair (or, as Jules puts it, this “sprig on the great bush of life”) save humanity? Find out for yourself – and prepare to be both charmed and amused.

boom plays through Sunday, Jan. 31, at San Diego Repertory Theatre. Shows Wednesday at 7 p.m.; Thursday, Friday and Saturday at 8 p.m.; Sunday at 2 and 7 p.m. For tickets, call 619-544-1000 or visit www.sdrep.org.

Miranda (Jo Anne Glover) is 38 when husband Nick (Stephen Elton) suggests they have a baby. Though the world of diapers, braces and PTA meetings isn’t the one Miranda had in mind when she married, she eventually agrees, to please Nick – and then the problems begin.

MOXIE Theatre presents Lisa Loomer’s comedy Expecting Isabel through Sunday, Feb. 7, at the Rolando Theatre. Jennifer Eve Thorn directs.

Glover is winning as worrywart Miranda, queen of the worst-case scenario, whose childhood with Episcopalian, martini-swilling mom Lila (Robin Christ) is ot remembered fondly.

Nick, on the other hand, is a happy-go-lucky sort, a struggling sculptor from a loving and stereotypically voluble Italian family from the Bronx. When Nick announces they are “working on” a baby, incredulous sister Pat (Sandra Ruiz) mutters, “They’re working on it and I get knocked up if I sit funny.”

But when nature doesn’t take the desired course, Miranda and Nick embark on the road of the fertility challenged, and the whole catalog of fertility drugs, in-vitro fertilization attempts, self-help books, medical specialists and support groups are fodder for Loomer’s comedy-sketch mill.

By the second act, failure is acknowledged and Nick and Miranda move on to the next step: adoption, offering a similar number of hoops to jump through and myriad possibilities for failure: another support group, meetings with young birth mothers-to-be (who may decide to change their minds), marriage counseling and my favorite, the Adoption Option, a placement service run by facilitator Judy (Christ).

It’s in this act that Loomer loses some of the sharpness of the humor and gets a bit preachy. But this is a fine cast, six of whom play some 27 characters among them. The piece is zippy of pace, the result never in question, and though the wisdom of bringing a baby into a household where only one of the couple is sold on the idea is questionable, Loomer at least manages to keep the giggles coming.

MOXIE Theatre’s production of Expecting Isabel plays through Sunday, Feb. 7, at The Rolando Theatre. Shows Thursday through Saturday at 8 p.m.; Sunday at 2 p.m. For tickets, call 858-598-7620 or visit www.moxietheatre.com.