This'll cheer you up. I read an article about advertising the other day and stumbled across a concept that seems so nakedly evil, I was amazed it exists. Particularly because it's embraced by the makers of Weetabix.

It stems from the notion of "brand ambassadors", that tit-awful phrase for stars who become synonymous with a commercial product in exchange for a mere fortune. The idea is that when you glance at, say, an Activia yoghurt in the supermarket, thanks to its high-profile star-fronted advertising campaign, you'll think of Martine McCutcheon and make positive connections to the fun times you saw her getting drooled over by Hugh Grant in Love Actually or run over by Frank Butcher in Albert Square. And your basic ape brain, which perpetually craves love and acceptance, will make you chuck said yoghurt into your basket in a desperate attempt to make some of that McCutcheon magic rub off on your own sorry bones.

Because you want to be Martine McCutcheon. You want to be her so badly you're prepared to eat her. In the form of yoghurt. Yoghurt that also improves your ability to defecate. That's what Activia's really about, of course – regulating your guts so you defecate better. In a franker, more honest universe, Martine would defecate in the commercial. But she doesn't even blow off. She just smiles a lot. Although come to think of it, she does smile a bit like someone who's just evacuated their bowels after several days of trying. So maybe she's still on-message.

Celebrity endorsements have existed since the dawn of advertising, but it's only recently that the celebrities have come to be thought of as "brand ambassadors". When Gareth Hunt walked down the street during the 1980s, passersby didn't think: "There goes the Nescafé brand ambassador," they thought: "That's Gareth Hunt." And then they mimicked the shaking-a-fistful-of-coffee beans gesture at him, which was easy to misconstrue.

But while coffee might've been your first thought upon spotting him, there was a clear mental separation between Hunt and Nescafé. Nowadays when a star signs up to be the face of a product, they're expected to embody its values in everyday life, as though they've joined a religious order. That's why Gillette dropped Tiger Woods when it transpired he'd stuck his penis into lots of women. Sticking your penis into lots of women is perhaps not a concept Gillette wants associated with its male grooming products. Masturbating alone – is that the Gillette way? Possibly using a handful of shaving foam?

But the notion of "brand ambassadors" has now filtered into the everyday world. "Influential individuals" – not celebrities, just "influential" people engaged in "normal life" – are being paid by marketers to promote goods, by wearing branded clothing or enthusing about certain products online. Fairly menacing, you might think, pausing briefly afterwards to wonder why your eyes are crying. But it gets worse. Because they're doing this with children.

Yes, children are being paid to wear corporate logos while out and about. The news passed me by at the time, but back in July, it was reported that Weetabix had recruited 15 especially active kids to wear special Weetabix-branded clothing "on their busiest days", in order to show that "youngsters who eat Weetabix can pack more into a day than those who don't". Weetabix spokesthing Sally Abbott was quoted as saying: "Parents know why Weetabix is great for big days but we need to find different ways of getting that message across to kids."

No you don't, Sally. You just think you do. And in the process, you've got a message across to me: that Weetabix is evil. Until I stumbled across this months-old story, I liked Weetabix. I associated Weetabix with the lovable cartoon Weetabix skinhead gang from the 1980s. I couldn't eat enough of those guys. Even ate a couple this morning. But now I associate Weetabix with a nightmare vision of a dystopian future in which children are brand ambassadors. Not so appetising.

The Milky Bar Kid was an early child "brand ambassador", but at least he knew his place: inside the TV. He didn't turn up at your school in his cowboy outfit. Today, if advertisers thought they could get away with it, they'd pay kids to have that cowboy outfit permanently stitched onto their skin. Which would actually be quite cool if you got to be the Honey Monster.

At least logo-branded clothing is easy to spot. The notion of companies paying for "online endorsements" from kids is even more sinister, although parental consent is required. Thanks in part to the media spooking parents into believing there's a deathtrap full of paedophiles round every corner, kids are kept indoors and bombarded with sales propaganda as it is. They grow up being told, in the most sophisticated manner possible, that products are the ultimate source of self-worth. A recent Unicef report concluded that British kids are desperately unhappy: they have an abundance of toys and products and a lack of attention from their parents.

And we wonder why the ones who can't afford these products kick in the windows of Currys and Foot Locker, risk arrest for a gizmo, land in jail for the sake of a shoe.

But now even the ones who recognise how the media clobbers them over the head with an aspirational mallet, who try to filter out the background consumerist dance beat – they can no longer trust their own friends when chatting online. Those schoolfriends may soon be "brand ambassadors". Not even friends any more, but mascots. It'll backfire, of course. Kids are kids. There'll be brand ambassadors outed as bitches and bullies. One day a brand ambassador will shoot up a school, and the potato snack company that paid him to endorse its products online will rush out a press release explaining that his actions don't embody their values, which traditionally involve less screaming and death. And we'll all be sadder and wiser. And we'll buy something different. For about three weeks.

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