A warning poster appeared in my local supermarket last week: "No flour or eggs will be sold to anyone under the age of 16." Visions arose of long queues at the checkouts, youthful-looking customers desperate to get a last-minute Victoria sponge in the oven, screaming at staff that they were well past the age of consent. What on earth was behind this poster? Is there a new baking method that produces crack cocaine? Or have teenagers worked out how to get high on home-made pancake mix?
Sadly, no. It was just another strange symptom of the nanny state, an attempt to rain on the Halloween parade. While I have never seen the damage done by flour-throwing trick-or-treaters - and, who knows, maybe it can be substantial - banning the sale of these items to under-16s seems pathetic and draconian. There are plenty of other shops where they can buy these items anyway.
What if they are legitimate shoppers, running an errand for their parents? Or even children who care for and cook for their own parents? And surely, if you were the sort of person who was going to wreak Asbo-inducing havoc with domestic comestibles, you would soon enough come up with another, far worse plan?
Still, we shouldn't be surprised. It is not easy to keep up with what is legal these days. There are all sorts of recent new prohibitions - no smoking indoors, no cigarettes for the under-18s, no biscuits for fat children. Barely 24 hours goes by without a new law that forbids you from doing something today which was perfectly acceptable yesterday.
Of course, no one condones teenagers harassing old people, defacing other people's property or even messing each other up in the street. But you have to imagine what it must be like to be a 16-year-old these days. These prohibitions must make adults - and the state - come across as hectoring, terrified and insecure.
The policing of teenage behaviour is becoming desperate. In a recent newspaper article, parents anonymously revealed how they log on to their teenage children's Facebook pages and snoop on their text messages and emails. In their minds, their children's safety was paramount. As far as they were concerned, this overrode any notions of betrayal of trust. But several had crossed a line without realising it.
One father proudly boasted about how he had posed as another teenager online to get his 15-year-old daughter to disclose details about her sex life to her new internet "friend". He eventually revealed himself and prevented her from having sex with an older man. You have to wonder which is the more traumatising: having sex at too young an age or finding yourself making friends with your father when he is posing as a teenager in a chat room.
There is a deep unease towards older children and teenagers at the moment. Perhaps it is a backlash against the laissez-faire child-rearing popularised in the 1970s, when parents were told that children know best and thrive without rules and regulations. But while it has always been extremely doubtful that these hippie attitudes were taken up in many households, none theless they have entered popular myth.
In the 1990s, this morphed into the "blame the parents" riff that is now standard. It is a dangerous argument because, if you extend it to its logical conclusion, often what it is really about is the residual belief that women should be at home looking after children.
The shopping list ban is part of this: it shows that, as a society, we don't trust children not to make a mess of even the smallest of things.
Too much supervision and suspicion, though, is just as dangerous as letting kids do whatever the hell they want. If I were a teenager - trusted with neither flour nor my own text messages - I would be deeply paranoid. Which would only make me want to go out and throw an egg in someone's face.