On the Amazon page that sells the world’s smallest mobile phone, the reviews are mainly about putting it into your bottom. ‘What more can you ask for,’ writes a man called John Doe, ‘than this ergonomic phone that fits snugly in your rectum?’ Sean writes, ‘No anal problems!!! Didn’t hurt my bum at all!’ Pookey says it’s ‘easy to butt dial’, although may be talking about something else. For another customer, the big problem is that ‘you can barely feel the vibrate function when it is concealed’. Although don’t worry, because ‘Bluetooth reception is OK’. Why ever take it out?

Many of these phones are advertised under the slogan ‘Beat The Boss!’, which initially is something of a puzzler. What sort of jobs do these people have where they aren’t allowed phones or even pockets? Or is this perhaps a contest? ‘Now, Jenkins,’ says the boss. ‘I can manage a Nokia 3310 and, at a push, one of those old flip-cover Sony Ericssons. And your job is on the line, unless you can go up to three.’

It turns out, though, that the Boss is not a boss. Rather, it is a Body Orifice Security Scanner, otherwise known as a large grey metal chair of the sort you will often find on the way into prisons. Normally, this is what these phones are for — smuggling into jail. Nor do they always go into your bottom (also known as your ‘prison wallet’). Sometimes they go into your Mars Bar, which is not a euphemism.

I know this thanks to a documentary I saw late last year, which was all about how much footage now leaks out from prisons after being filmed on smartphones. I’m not sure how they get the smartphones. You can’t fit one of those into a Mars Bar or a bottom without making a terrible mess. Or at least not unless they’re very roomy.

According to the Daily Mirror last week, more than 20,000 mobile phones were seized in English and Welsh prisons last year. I could not tell you how many were in bottoms versus Mars Bars, and frankly I’m a bit disturbed that you want to know. With a total prison population of less than five times that, though, it seems fair to suppose that pretty much every prisoner has access to a forbidden mobile phone.

This week, meanwhile, the BBC reported a ‘working assumption’ that each jail had between three and five corrupt officers, supporting the smuggling of various contrabands into jails, by whichever chocolatey medium they preferred. They’d got hold of one of them, a man called James Almond, who was given a 12-month sentence for doing just that. He’d been intimidated by a prisoner, he said. Then he’d made a lot of money.

Prisons are a mess right now. In a long-term, drip-drip, never-quite-the-main-story sort of way, every week brings a new slew of horror stories behind bars, from overcrowding to drug epidemics, to record-breaking rates of suicide and self-harm. I visited the private Winson Green prison in Birmingham last autumn, and the main thing I remember inmates spoke to me about was how hungry they were. Six weeks later they were rioting, apparently over cold showers and the temporary closure of the gym.

Apparently there were also 2,580 fires in British prisons last year, or about 50 a week. Prisoner numbers have almost doubled in England and Wales since 1991 (although not, strangely, in Scotland) while prison officer numbers have dwindled. Austerity is happening in prisons. Liz Truss, the Justice Secretary, seems scared of letting people out of them, but also scared of paying much more money to keep people inside them. Sometime soon, something terribly bad will happen, and more people will care.

That doesn’t explain the phones, though. Are we all wholly comfortable that Amazon, the UK’s biggest online retailer, is selling devices explicitly designed, marketed and sold to be illegally smuggled into prisons? Personally I’m not, although I’m also genuinely stumped as to what we ought to do about it. In a free society, the idea of an explicit moratorium on any handset smaller than, say, the diameter of a sphincter is obviously problematic.

The same, actually, is true of Spice, the horrible prison drug of choice. It was outlawed last year, but until then you could buy it in corner shops. Even today, it is incredibly easy to buy online; posted globally from anywhere, turning up via airmail, it is still legal. I’m not sure what law you could pass to stop this happening. Like the phones, it seems to be a problem that smuggles itself in, bonded to the freedoms we don’t want to do without.

Prisons, of course, are places where people ought to do without them anyway. Clearly they need to be less porous, and clearly one major way of doing that would be to spend more money on them, from better scanning equipment at the gates to better-paid staff more prepared to don their rubber gloves and delve.

The lesson of the Beat The Boss bumphone, though, is perhaps that none of this will ever be quite enough. No wonder they can’t control the inside, when the outside, too, increasingly answers to nobody. The internet is not a shop, or a mail-order advert in the back of Viz. It is everything, always, at our fingertips, for ever. It is bottomless. And thus ripe for exploitation by people who are not.