Puppy love. It's the confusing -- but exciting -- emotion that makes "Little Manhattan (search)" go 'round.
In the movie, opening this weekend, 11-year-old fifth-grader Gabe Burton (Josh Hutcherson (search)) is too busy practicing place-kicking and scootering around his Upper West Side apartment to pay any attention to girls.
That is, until the fateful day when he starts taking karate lessons -- and falls hard for his classmate Rosemary Telesco (Charlie Ray (search)), a girl he's known since nursery school.
Told from Gabe's point of view, the story is a funny and touching look at first love -- and how kids go from yelling "cooties!" to cuddling.
Even so, the stars of "Little Manhattan" tell The Post, they did sweat the kissing scenes.
"I'm not really that experienced yet, because I just recently started liking girls," admits Josh, who turns 13 next month, and whose last film was "Kicking and Screaming" with Will Ferrell.
"I never really thought about it until the actual night we shot it," says 13-year-old Charlie (short for Charlotte).
"All of a sudden, I realized we would have to kiss, and I thought, 'Yeah, it's weird' and I could tell he was pretty nervous about it, too.
"It's not like a French kiss or anything," she explains, hastily. "It's just a little peck, so after the first couple takes, it became a regular thing.
"We had to do it about 15 times, so it wasn't that bad after a while."
Set and filmed almost entirely on location on the Upper West Side of Manhattan, "Little Manhattan" features such familiar sites as Central Park's Boathouse, Strawberry Fields, Fairway supermarket, the Hotel Carlyle and the Hayden Planetarium.
But Gabe and Rosemary's biggest adventure is when they sneak off and head downtown to Greenwich Village -- on the subway. Without parental supervision.
"They had all these extras and the camera crew in the subway car [with us]," recalls Charlie, a native New Yorker who lives in TriBeCa and who, in real life, started taking the subway alone this year, to go to private school.
"I guess they reserved a line or something -- it was cool."
Heading home, the pair skip the subway and, instead, hop aboard the scooter Gabe's folded up and carried with him. Together, they scoot along Hudson River Park. (And you thought Woody Allen was romantic!)
Surprisingly, there were no scraped knees or worse during the filming -- and no stunt people, either.
Turns out that Josh, who lives in California, is quite the scooter expert. That's clear in the film's opening scenes, when he's hopping curbs and zigzagging across sidewalks.
"Since I was 8 or so, me and my little brother always had Razor scooters that we rode around our neighborhood all the time," Josh says.
"That was our mode of transportation back home in the suburbs. I had to practice a little bit [for the movie] because it was a bigger scooter than I'm used to."
Something he didn't need to practice was the scene where Gabe tells Rosemary that he hates her. He then has a full-on crying fit in his room -- complete with slobbering, kicking and screaming.
"It's this thing called 'sense memory recall,'" the veteran actor tells The Post.
"Where something dramatic happens in your life, whenever you need to cry in a scene, you just think about that and let it out.
"They had me do some [takes] that were over-the-top, really cheesy, just to make it funnier. Every time they said 'cut,' I would go from over-the-top crying to laughing.
"That's what ended up in the movie, because it was really funny."
While "Little Manhattan" doesn't end on the typical romantic comedy note -- you know, where the guy gets the girl and they live happily ever after -- the cast parted on good terms.
Though they live on opposite coasts, Charlie in New York and Josh in California, they still keep in touch.
"We don't get to see each other a lot," Charlie says. "But we e-mail sometimes."