If your boyfriend's birthday is coming up and you're low on cash, you can always write him a starring role in a play.

That's what Vanessa Claire Smith did for French Stewart in 2010, surprising him with a script about his idol, Buster Keaton.

Two years later, "Stoneface: The Rise and Fall and Rise of Buster Keaton" just opened to glowing reviews at Sacred Fools Theatre in Hollywood, and the newly minted Stewarts are coming up on their first wedding anniversary.

But because even happy endings have their hitches, a hot Sunday in June finds the couple cooling down in a bar around the corner from Sacred Fools, after a broken air conditioner made a matinee performance of "Stoneface" especially grueling.

"Next time, you're writing me a little Noel Coward-style tea party where I never get up," says French.

"My first play bought the theater that air conditioner," Vanessa says with a sigh.

That first play, in which she starred with her co-author, Jake Broder, was "Louis & Keely Live at the Sahara," the story of jazz greats Louis Prima and Keely Smith told through their music. After earning Sacred Fools the air conditioner in 2008, it moved on to the Geffen, where it ran for eight months.

French was performing in "Matthew Modine Saves the Alpacas," also at the Geffen. The casts socialized in the green room.

"He would flirt with me a little bit," recalls Vanessa. "I was kind of shy and he's obviously gregarious, and I wasn't sure if he was joking or actually flirting."

"Yeah, well, there's a 13-year age difference," puts in French (he's 48; she's 35). "So I felt like it was a fine line between, you know, fishing for a nice lady and being some pervy creep that nobody wants to see in the green room. So I'd flirt in a funny way."

But when Vanessa saw French's show, "my curiosity went to an instant crush, because I had no idea that he was that good. It blew my mind. That night on my way home, I was like, 'I'm just going to do this.' I called and said I'd be in a tiki bar near my apartment if he wanted to say hi."

"I didn't realize until then that my Prius could do a doughnut in the opposite direction," recalls French.

French, best known as Harry Solomon on "3rd Rock From the Sun" (1996-2001), had been working in the theater and taking pratfall-heavy roles in movies such as "Home Alone 4" and "Inspector Gadget 2" ever since — and feeling battered and unappreciated.

Vanessa agreed. "I didn't think people understood how good and how versatile he was. In my mind, he's like a Philip Seymour Hoffman."

In that fateful tiki bar, she says, "It came up that his life's dream was to be Buster Keaton, but he thought he was too old."

She determined to prove him wrong. "I didn't know anything about that time or those people, but I love history, so it was a pleasure to order books and documentaries. And to me, the interesting part of Keaton's life was actually this part, where French is. I'd see him at the Geffen doing flips, and then he'd limp to his car. Like Keaton, he was giving everything he had to entertain these people."

Writing the script in secret as their romance blossomed, she hesitated to show him. "Since he held Keaton in such a reverent way, I didn't want to ruin it for him. But when I felt I could tell the story correctly, I thought, 'Maybe I'll give it a shot.' Also," she adds dryly, "I didn't have a whole lot of money at the time, and I needed a birthday present."

The surprise resonated with French. "I knew it was good because the more I worked on it, the more I realized, 'Oh!' And then the things I originally wanted changed, I was like, 'Put it back. Sorry.'"

Vanessa nods, with a smile of vindication — although as a writer, she encourages collaboration. She hoped all along, she said, that director Jaime Robledo and the "Stoneface" cast, including Joe Fria, who plays the younger Keaton, would make the physical bits their own.