It always goes something like this: "Please Read! Your Safety Matters!" And it's an e-mail about some horrible story that makes you want to run and hide under a rock (after you've sent it to all your friends).

The one I got last week was about a "Smart woman" who just BARELY managed to save herself. Apparently, this "woman" had gone out to the mall parking lot and found she had a flat tire. She was about to fix it, when a nicely dressed man with a briefcase walked up and offered to help. She gratefully accepted.

When he was done, he threw the tools in the trunk, shut it and asked for a ride to the other side of the mall, where he'd parked his car ... but something felt strange. She told him that first she had to run back to the mall for something. Run she did. When she returned with a mall guard, the man was gone. They opened the trunk, and there was his briefcase ... filled with rope, knives and duct tape!

"When the police checked her 'flat' tire, there was nothing wrong with it. The air had been deliberately let out," read the e-mail. "Please forward to all the women you know. It may save a life."

Yeah, and so may warnings about the Abominable Snowman.

Look, this story is clever. It's creepy. It's just like the ones we used to tell at slumber parties: "Their wish on the monkey's paw had come true!" It sends a chill up your spine, apparently leaving your brain too frozen to ask some simple questions, such as:

—A serial killer lets the air out of someone's tire at the mall and then hangs around hoping the owner will come back, what, an hour later? Two? Four? He just keeps hanging around?

—No one notices him?

—He just hopes that the car belongs to a single lady and not a family of five?

—He bothers with a huge, elaborate plot when he could just snatch someone from a seedy rest stop?

As my friend who passed this along noted with annoyance, "Please. Has this EVER happened to ANYONE?"

And the answer is: It is an urban myth. You can find it, word for word, on Snopes.com, the very valuable website that tracks and cracks urban myths.

Now, obviously, urban myths have been around for a long time. Spider eggs in Bubble Yum, anyone? What's different is that today, thanks to social media, they keep getting recycled, almost always by well-meaning people. Unfortunately, those people are making the world a little LESS safe each time.

After you've read your third or fourth e-mail about a good Samaritan who turns out to be more devious than the Joker, it's hard to trust anyone who says, "Can I lend you a hand?" It even becomes hard to OFFER a hand, knowing how suspicious you may look. Thus begins the breakdown in community. People feel stupid reaching out.

Moreover, urban myths portray a society in which the worst is commonplace. Just the other day, my friend told me she was scared to take her eyes off her daughter while shopping because she heard of a little girl who was snatched from the aisles of a Walmart and found minutes later in the bathroom with half her head shaved! (The better to disguise her and smuggle her out.) That's an urban myth that dates back to the '50s, if not before, according to Snopes.com. The fact that it never dies means parents still are being scared out of their wits by an event that never occurred.

Really, why would a predator waste valuable getaway time staying in the store? What about all the hair on the floor? And how common are child snatchers anyway?

In truth, they're very uncommon. Ditto, serial killers with butcher knives in their briefcases. But when we are warned about them constantly, they start to seem as common as a shopping trip turned deadly.

Or an e-mail forwarded by a friend.

Lenore Skenazy is the author of "Free-Range Kids: How to Raise Safe, Self-Reliant Children (Without Going Nuts with Worry)" and "Who's the Blonde That Married What's-His-Name? The Ultimate Tip-of-the-Tongue Test of Everything You Know You Know — But Can't Remember Right Now." To find out more about Lenore Skenazy ([email protected]) and read features by other Creators Syndicate writers and cartoonists, visit the Creators Syndicate Web page at www.creators.com.