Friday evening. Walking down Highgate Avenue towards Archway Road, I hear someone shouting at the very top of their lungs. A male voice, possibly having some terrible domestic argument. I get to the junction and it turns out the shouting is coming from the phone box by Highgate Tube station. Are there two people in there?

The door to the box opens, and the shouting man is revealed to be alone, doing his screaming down the phone. Sometimes he is half out of the door, stretching the phone cable to breaking point, sometimes he is back inside.

As he is constantly ramming the phone back onto the hook, then picking it up again and resuming his screaming without dialling, I revise my initial notion that this is one half of a genuine argument. He is screaming at no one.

‘AND YOU WILL DIE IN A TERRIBLE EXPLOSION!’ The voice is so loud that, in the moments when he opens the booth door, it can be heard a block away.

He’s in his twenties: white skin, long brown hair, beard, carrier bag, casual clothes. He seems very clean, scrubbed and not scruffy at all, at least, not in the stereotypical crazy tramp or ‘alkie’ manner. More scruffy in the trendy, works-in-TV way.

In fact, he bears more than a passing resemblance to Justin Lee Collins, the bearded comedian and Channel 4 TV presenter. Given this sort of surreal incident could be something from a prank programme like Balls Of Steel, I wouldn’t rule out this possibility at all.

He finally exits the phone booth and walks to the pedestrian crossing. I am standing on the other side, facing him, waiting to cross. And naturally I am absolutely terrified. Half-past eight on a Friday evening, barely two minutes after leaving my front door, and already I want to go home. There is no getting away from this: I am going to have to pass by a madman.

I brace myself as the lights change.

He walks past in silence. I begin to sigh in relief.

Then I leap out of my skin.

Behind me, at the top of his lungs, he turns and bellows at me:

‘OR TAKE IT!’

At least, I’m pretty sure that what he says. A bizarre fragment of a sentence.

And then he continues walking away, up Jacksons Lane. I now suspect he’s an outpatient of the local mental health institute. Or an inmate that’s been let out for a while, as part of what is now called Care In The Community. The hospital in question is unfortunately located close to Suicide Bridge. Every now and then, the traffic is stopped, the police are called, and another inmate is talked down.

Thinking it’s all some TV prank, as I did here, is often my default reaction to anything unlikely in my life. I look for the hidden cameras. Just as I did when auditioning at the ICA for a living art exhibition a couple of years ago. With the hiring of actors to initiate philosophical discussions with visitors, put them standing around in empty gallery rooms, and then call this his art, I came away utterly convinced the artist – Tino Sehgal – was an actor himself, and that the whole exhibition was a TV parody of Turner Prize-style conceptual fare.

He’s since gone on to to set up similar shows around the world. Maybe he still IS an actor, and it’ll take a full lifetime for his jolly wheeze to be rumbled, like the Cottingley Fairies. Actually, if a conceptual artist dressed up his actors as Edwardian fairies, that’d be both pretty to look at AND a comment on faith and the art of believing things. You could call the installation ‘Religion’, ho ho. Not bear suits, though. Been done.

Not that there’s anything wrong with a career where confidence is the sole dividing line between genuine and fake. Goodness knows the service industries are full of fake positions: jobs that don’t seem to do anything. Some of my friends with well-paid, jet-set day jobs in high finance have told me their baffling, jargon-filled positions in ‘consultancy sourcing solutions’ mainly consist of being paid huge amounts of money for sitting in an office all day doing impersonations of work. Acting, essentially. Imitation Of Work.

Every four months or so, they tell me, they hastily put together some sort of presentation, so they can renew these blissful circumstances for a bit longer. Just like being a student again, except with a salary and a luxury flat. What is a job interview if not a confidence trick? A game with winners and losers, like any other.

But there is real work to be done somewhere along the line, of course. In which case, the hoax element can work the other way:

BBC friend: I’m doing three people’s work at the moment. Two jobs in my department haven’t been filled. So I’m doing their jobs as well as mine, all at once.

Me: That’s terrible. Shouldn’t you ask for more money? Or tell your bosses to hurry up and fill the vacant positions?

Friend: Oh no. I love having too much work. I’ve never been happier.

See also the people who fill their days off with decorations and DIY, rising at 6 am on a Sunday to paint the spare room, or drill holes in the wall, for no reason whatsover. Some are genetically disposed to hard work. Others to doing absolutely nothing. It all balances out. It’s really just a question of getting paid for whatever it is you’re disposed to do. Or not do. Or appear to do. Perhaps you can get a wage for screaming in a phone box. Submit it for an art prize, stare out the world with confidence, and get paid that way.

Me? Well, I know now that writing is the only thing that makes sense to me. Publishing it to be read as soon as possible (i.e. online) doubly so. It’s why I became an accidental blogger in 1997, before the word was coined. It quietens my mind. It stops me from going insane. It helps me work out who I am. Like standing at the edge of a swimming pool, the only hard part is getting started, getting wet. Once I sit down and get on with it, I’m utterly happy. I’m in the swim.