Shortly before she was to open “Grease” on Broadway in 2007, actor Laura Osnes and her husband, Nathan Johnson, were telling a reporter how they met on stage in “Aladdin” at Children’s Theatre Company in Minneapolis.

It was a kiss they shared on stage, Johnson mooned, that shot stars through the sky and set their fate.

“What?!” Osnes said, half amused at her hubby’s reaction. “That was just a stage kiss!”

Johnson should have taken heart in his new wife’s coolness, given the thousands of kisses and cuddles that were in Osnes’ future over the next year, playing Sandy in “Grease.” But the simmering chemistry — or fakery — of a stage kiss provides endless fodder for real-life speculation and fictional scene making. (Anyone remember Rob Petrie’s hilarious fit of jealousy when Laura had to kiss a neighborhood Lothario in a community theater rehearsal?)

Sarah Ruhl became curious about the phenomenon after watching actors rehearse kissing scenes in plays she had written. In an essay for the Playwrights Horizons website, Ruhl wrote about these people who would come to work and then kiss other people.

“Kissing on stage is both real and not real,” Ruhl wrote. “There is a physical reality to the act, but the context renders the action fake.”

How strange, she thought.

Ruhl, one of the most interesting playwrights of the new century, put her imagination to work and produced “Stage Kiss,” which had its premiere at Playwrights Horizons in 2014. The Guthrie Theater opens a Minneapolis production on Friday with Stacia Rice and Todd Gearhart portraying two actors who are former lovers who get cast in a 1930s melodrama that includes lots of kissing. The play, then, is about the very subject of what’s real and not real.

“Is it an actor kissing an actor, or is it a person kissing a person?” Rice asked in a recent interview.

It’s both, of course, but can the human actor suppress the very real physical and emotional reactions inspired by a kiss — what playwright Edmond Rostand called “the pulse rising from the heart to utter its name on a lover’s lip: ‘Forever.’ ”

Or at least for the six weeks of a theatrical run?

Class is in session

Rice’s first stage kiss came from the lips of actor Ann Michels. The two are now fast friends, but Michels remembers rehearsals for the play “David’s Redhaired Death” in 2001 as being decidedly awkward.

“She was really nervous about it,” Michels said. “She had never kissed anybody before and the director would say, ‘Could you get into it a little more?’ and we’d try and then Stacia would say, ‘OK, that’s enough for today.’ ”

Michels, currently doing no kissing (on stage) as the title character in “Mary Poppins” at Chanhassen Dinner Theatre, said stage kissing “has never been weird for me” if it is essential to telling the story.

“Understanding that the audience is going to get a thrill and they get to see the enhancement of the story makes it all worthwhile,” she said. “As in ‘Hair,’ we stand there and take off our clothes because it serves the play.”

A conversation with Michels on the topic recalled a beautifully poignant moment in the 2008 production of the musical “Parade.” She and actor Dieter Bierbrauer had recently ended a long relationship, and yet there they were, portraying lovers on stage.

“It was complicated, sad, and yet we had this job to do,” she said. “Sure, it affected us. I really had to applaud [director] Peter Rothstein for letting us do that. There were a lot of directors who would have been afraid to put us together.”

Strangers on the stage

Rice and Gearhart have no history. Director Casey Stangl said actors in major regional theaters frequently are cast without knowing each other. Rice was chosen first and Stangl found Gearhart in New York later.

“For a month before you start, you know there is this person out there you haven’t met,” Gearhart said. “Either this will be awful or … until you kiss someone, you don’t know.”

Stangl said she cast them because she knew they would look good on stage.

“I had a good vibe, which is just as important as acting ability when you’re going to be spending this intense period together,” she said.

Gearhart was wed only two years ago; his wife, an academic, has no theater experience and was naturally curious about the situation. Her husband was traveling halfway across the country, so she googled Rice to see who this woman was.

Her instinct was not unique. The Internet is loaded with sites that offer advice about how to kiss on stage, and how to deal with your feelings when your boyfriend or girlfriend is mashing someone in front of you and acting like they love it.

“I told my wife, ‘What if I said that every day at 7:45, I was going to kiss you?’ ” Gearhart said. “It would take away the spontaneity.”

He and Rice never would even think of kissing goodbye at the end of a day of rehearsal.

“That would be rooted in something else,” he said.

Following the protocol

Rice agreed and said there needs to be a strict division between stage and reality. Even in rehearsal and performance, there are techniques to “keep it safe,” she said. There is the five-count kiss, the seven-count, the open mouth but no tongue. Also, there are lots of toothbrushes and breath mints around. At an interview, they both indicated they’d have to do something about the coffee they were drinking — which they both usually avoid during rehearsal.

“You have to be professional and courteous,” Gearhart said.

One of the weirdest stories about an actor breaking all those rules involved Rod Steiger and Julie Christie in the 1965 movie “Dr. Zhivago.” Steiger told David Lean that if the director would let the film roll after he kissed Christie in a particular scene that he would kiss her again and “I’ll stick my tongue down her throat” to provoke a certain reaction. He did, and if you watch the scene with that knowledge, Christie’s squirming — which appears very real — totally made the shot.

What worked on film, though, would not hold up in the theater, where actions need to be repeated eight times a week for many weeks. Gearhart said they counted 35 kisses in the show. There will be moments when it feels real, when the body reacts to the stimulation of all five senses. Actors are human beings who by necessity need to intellectually categorize their work at the same time they are making themselves vulnerable and emotional. Watch closely next time an actor “cries” on stage. Are there tears, or have you been fooled by loud sobs that come from the larynx, not the heart?

“The more something costs you, the more it means,” Gearhart said.