Here’s this week’s Smartmom from the Brooklyn Paper:

What happens in the idyllic brownstone neighborhood of Park Slope if you see a teenager smoking a cigarette on Seventh Avenue?

Obviously, you’d tell the parents of that child if you knew them. Right?

Smartmom’s neighbor, Mrs. Kravitz, recently grappled with this question after seeing a friend’s teenage daughter walking down the street smoking a cigarette.

She even made eye contact with the girl, who hid the cigarette behind her back when she spotted Mr. Kravitz.

“You don’t have to hide it,” Mrs. Kravitz said nicely.

For days, Mrs. Kravitz struggled with her secret. Should she tell her friend? She knew her friend would want to know. But how and when should she tell her?

To make matters worse, her friend was about to go on a special vacation and the timing didn’t feel right.

So she discussed the matter with Mr. Kravitz, who was adamant that she should tell her friend. It doesn’t matter how or when you tell her, he said. Just do it. She needs to know.

Still, Mrs. Kravitz worried that this information might ruin her friend’s vacation. She and Mr. Kravitz weighed the options and finally decided to tell their friend when she returned from her trip.

Just hours after her friend got back from her vacation, Mrs. Kravitz told her what she’d seen. And her friend, still suntanned and basking in her vacation glory, was very grateful. And very sad.

Interestingly, she already knew that her daughter was smoking, but she hadn’t brought it up with her daughter yet. She was in deep denial about it.

“I was hoping that she was just trying it out or holding a friend’s cigarette,” she told Mrs. Kravitz.

Mrs. Kravitz’s friend removed her veil of denial like too much sunscreen and vowed to have a long talk with her daughter. A good deed was done and Mrs. Kravitz felt vindicated.

Smartmom brought this up with Tabloid Dad, when she ran into him on Seventh Avenue recently. Tabloid Dad is a producer for the Geraldo Rivera show, who has a 10-year-old son and a 3-year-old daughter. He takes a refreshingly honest and open approach to child rearing.

“Well, smoking cigarettes is better than smoking crack,” Tabloid Dad joked, but he quickly turned serious.

“When I was a teenager someone told my parents that he saw me drinking beer in the schoolyard. I made my mother tell me who told her. It was a guy who lived on our street. I still hate the guy,” Tabloid Dad said.

Still, he thinks it’s a good idea for parents to talk to their kids about whether they’re smoking or drinking.

“Just so they know you’re paying attention and that you’re not so absorbed in your own life that you don’t know what’s going on with them.”

Tabloid Dad did make one suggestion: If you are going to tell the parents that their kid is smoking or drinking, make sure that the parents don’t divulge your name.

That way the kid won’t hate you and you won’t humiliate your own child if anyone finds out that you’re a snitch.

Thanks for the good advice, Tabloid Dad.

Smartmom asked Tabloid Dad’s wife, Tabloid Mom, whether she would want to know if her daughter (the 3-year-old) was smoking.

“Absolutely,” she said without moment’s hesitation.

“When I was a kid, I caught my sister smoking and she told me they were candy cigarettes. When I asked her why smoke was coming out, she told me it was the sugar,” Tabloid Mom said.

Which just shows that kids will do absolutely anything to pull the wool over their parent’s eyes. Be prepared for any excuse: “I was holding my friend’s cigarette”; “That wasn’t me”; “I was just trying it out”; “I only smoke sometimes”; “I only smoke when I’m with my friends.”

The sidewalks have eyes. That’s what they say here in Park Slope, where parents routinely report on each other’s children. This is a neighborhood full of people who did crazy things when they were teenagers, so they know the score. They know all the stories, all the tricks.

Even Dumb Editor, who grew up in the suburbs, knows how to read the furtive eyes of a group of kids congregating outside Maggie Moos. He may have been born at night at Dobbs Ferry Hospital, but he wasn’t born last night at Dobbs Ferry Hospital.

All this doesn’t mean that the teenagers are any less crazy than their parents.

But around here, if someone’s parents see them doing it, chance are they’ll find out.

Knowledge is a good thing. But it’s still up to each parent to figure out how to talk to his or her children and help them steer clear of dangerous activities.

That’s the hard part and that’s the part that goes on behind the doors of this idyllic brownstone neighborhood, where life isn’t always quite as idyllic as it seems.