When I was a teenager, one of my friends got a tattoo. Was it a big grinning death's head? Nope. Was it some kind of gang symbol? No. Was it big and scary? Er, no.

It was Winnie The Pooh. He did it primarily because he thought girls would find it cute, and I'm sure they did at the time.

Now he's nudging forty I'm sure it's a lot less cute, and if he ever gets sent to prison it's going to be the cutest suicide note ever inked.

I thought of him when Symantec sent me a note headed "twenty-somethings regret their digital tattoos".

Apparently The Kids post stuff on the internet without thinking about the consequences, and sometimes the things they post come back to bite them.

Symantec's study "revealed a devil-may-care attitude towards posting personal information on social networking and other websites, with over a third of under-25s claiming no concerns about what they are leaving online."

Of course they aren't concerned. Was my friend thinking "Hmmm, better not get this tattoo - I'll look like a right daftie when I'm forty?"

Of course he wasn't - and when kids post photos of their backsides, drunken exploits or other things that might eventually embarrass them they're not thinking about the future, either.

Searchable by anyone

According to Symantec's family safety advocate Caroline Cockerill, "They either don't know or forget that much of the data is searchable by anyone, and in many cases legally retained by the sites themselves, or stored in caches, even when the data appears to have been removed."

I think Cockerill is wrong. They do know. They haven't forgotten. They just don't care.

Young people do lots of dumb things, but it's not that they don't know better. I knew that smoking was dumb and dangerous, but I still started smoking.

I knew drinking two bottles of Buckfast and surfing on top of a Ford Transit wasn't very bright, but I still did it.

I knew that driving like a complete idiot wasn't particularly sensible, but I did that, too. I knew that pouring petrol over myself and lighting it was a bit risky, but WHOOMPH. And so on.

How old?

When you're a teenager, even thirty is an eternity away and you only think about the consequences of your actions when they actually affect you.

My insane driving career only ended when I miraculously escaped a car crash that, had it happened ten seconds earlier or later, would have pancaked me under a truck.

I stopped drinking Buckfast when I got fed up of waking up in hedges. I stopped setting myself on fire when I discovered that methylated spirit burns in a much different - and much, much hotter - way than lighter fluid does.

And now that I'm a wheezing, coughing wreck who needs a lie down after tying my shoelaces, I'm beginning to realise that my folks were right when they told me smoking was a stupid thing to do.

You'll have your own list of daft things you used to do but don't any more, I'm sure.

In the long term, The Kids are going to realise that posting too much online isn't very smart, either. Some will learn the hard way, others from seeing their friends learn the hard way, and eventually they'll all grow out of it.

Until that happens, our warnings will have as much impact as our impassioned, heartfelt and entirely accurate explanations of why all the music they listen to is crap.

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