For as long as I can remember, children have been told to not take candy from strangers.

Drug companies have spent billions on making their bottles and capsules "tamper-proof".

Depending on your preference, you can have your fruit and vegetables made safe for human consumption by buying ones that have either been grown organically with nothing on them, or ones that have been sterilized with radiation until they glow.

And even though anthrax has sort of turned out to be the Stockwell Day of bio-terror weapons (initially scary but not as big a deal as we feared, even if keeps coming back), it was enough to have people boiling their mail and calling the fire department every time they spilled the baking soda.

Why do we do all these things? Quite sensibly we don't want to be exposing ourselves to unsafe or unhygienic substances, especially if we don't know where they come from or where they've been. The world has been a pretty nutty place the last little while, so we've been walking around in a state of hyper-awareness about any and all threats to our health and safety.

So explain this one to me. The other day I was talking to a friend while she opened her mail. She's the kind of person who is very careful about anything that looks, smells, or feels odd. Not paranoid ­ just very cautious.

As we're talking she comes across a stick of gum stuck to a bright piece of cardboard in her mail. So what does she do? She puts it in her mouth.

Of course it's a harmless promotion by someone convinced that what the world really needs right now is more people chewing gum. But it shows that when even the most cautious of us are presented with a free treat from an unknown source, we forget all about terrorists, biological warfare and our mother's warnings, and our automatic reaction is to stick it in our mouth.

I've seen it first hand. My first job was in a grocery store. The Cheese Lady liked me, and gave me first shot at the free samples. It's a good thing too, because as soon as the doors opened, you'd think that people had never seen cheese before. Not only would they shovel fistfuls into their mouths, they didn't care that a couple dozen strangers had already pawed their way through the stack of cheesy cubes with their sticky fingers. After that, I wouldn't have one without a penicillin chaser.

But again, it was a free sample, so the regular rules of safety and hygiene apparently don't apply.

Once in a while you'll walk by someone in my neighbourhood standing in the middle of the sidewalk holding out a tray of broken cookies. I assume they're from the bakery around the corner, but they could be from Libya for all I know. The crowd that quickly gathers doesn't seem to care one way or the other. They're more interested in fighting their way to the front to get their mitts on the bigger crumbs.

I don't want you to think I'm immune. I've been tempted by the slightly irregular pound cake they set out on the grocery store counter too.

So I suppose there isn't any harm in free samples than come in the mail, as long as the return address isn't "Cave 9, Kabul".