DIETERS, BEWARE OF 3-FOOT-5 TEMPTRESS.

Byline: DENNIS McCARTHY 

Turn off the lights, lock all the doors, and don't answer the doorbell for a while.

Those cute little urchins in uniform - the Brownies and Girl Scouts - are loose on our streets. And, as usual, they're armed and dangerous.

They're knocking on our doors at home and setting up shop in front of supermarkets, banks and theaters with their caloric lethal weapons: Thin Mints, Samoas and those deadly delicious peanut-butter cookies.

Try eating just one at night, closing the box and going to bed. Forget about it. Can't be done.

I bought three boxes Sunday afternoon, and by the weather report of the 10 p.m. news, one-half box of Thin Mints was history. Gone.

I set a personal best in total lack of will power, eating 20 cookies inside 10 minutes - or, more to the point, inhaling a couple of thousand calories just before turning in for the night.

The Girl Scout motto is ``Where Girls Grow Strong.'' During their cookie drive, they should add, ``And Guys Grow Fat.''

Every year, I say the same thing. I'm not going to buy any Girl Scout cookies. I'm going to keep those cookies out of my house so they can't beckon me from the kitchen late at night.

And every year, the doorbell rings, and there's this 3-foot-5-inch ray of smiling sunshine standing on my front porch, looking like a cross between Orphan Annie and Shirley Temple.

``Want to buy a box of Girl Scout cookies, mister?'' she'll ask, with her lower lip quivering as if she's ready to burst into tears if I say no.

I don't know how people say no, because I can't. I cave and buy three boxes.

A few days of cookie-bingeing later, and I'm walking around the house looking like Orson Wells.

From what I hear, I'm not alone. Last year, more than 900,000 boxes of Girl Scout cookies wound up in stomachs throughout the San Fernando Valley.

``People are always telling us they shouldn't buy a box because they're on a diet, but they always do,'' said Yvonne Velasquez, product sales manager for the San Fernando Valley Girl Scout Council Inc.

She's the cookie supplier for more than 6,500 girls in 600 troops in the Valley. A dangerous woman for people who already can't get into two-thirds of the clothes hanging in their closets.

There's good news for people serious about their diets, though. That would be you, not me.

The Girl Scouts are peddling a new reduced-fat cookie, called Ole Ole, we can binge on without feeling like complete pigs.

This isn't an official study, and I can't verify any of the findings, but cookie supplier Yvonne swears that one of the people in her office took a box of Ole Ole to her Weight Watchers meeting a few weeks ago, and they passed the fat checker.

``They said she could have six Ole Oles and still not blow her points,'' Yvonne said.

The other good news is that there's an additional way you can support the Girl Scout troops and programs, buy a few boxes of cookies at $3 a pop and never gain an ounce.

Just don't take them home. Tell the girls to keep them, and later they'll be delivered to shelters, food banks and children's hospitals, Yvonne said.

Then again, you can just turn out the lights, lock all the doors and not go outside until after March 17, when the Girl Scouts will pack up their cookies for the year and go home.

For me, it's already too late. I've got more than two boxes of Thin Mints to go - just sitting there on my kitchen counter, waiting to beckon me forth late at night.