'No flinching,' Mark, our tutor, says.

At arm's length, one of my fellow students is holding a paper plate, overloaded with goo. I'm about to be hit in the face with a pie.

Mark gives me more instructions. 'I don't want to see you blink or scrunch up your face.' Then he nods to my attacker: 'Go for it.'

Whump. A slug of thick paste crunches into my face, instantly blinding me. Its weight is the first thing I feel; its density, followed by its coldness. I can sense it up against my hairline, I'm tasting it on my lips, smelling it where it's blocking my nostrils, and then I feel the paste sliding down my cheeks to drip from off my chin. Is this a nice sensation? I'm not thinking about that. All I'm worried about is how well I've done.

This isn't the first pie I've ever taken in my life, or even the first pie I've taken as a student on this course - we've had a short practice beforehand - but it's the first pie I've taken that's been videoed. The footage is going to be played back afterwards to the class so that my performance can be scrutinised. We're all going to be put to this test, and for no particular reason Mark has selected me to be the number one guinea pig.

It's still early days - maybe our second week at college - and, methodically, deliberately, we're being taught the basics: how to throw a custard pie; how to take one. In the previous lesson we'd been shown the way to chuck them, but only at inanimate targets; today we were being taught how to behave when we're their target. To the extent I'd ever given it any thought, I'd supposed that throwing a pie was the harder skill to master, and that being on the receiving end was the easy part. Who'd ever have guessed it was the other way round?

We watch the playback on a monitor screen almost immediately. (I've been given a quick chance to wipe the worst of the gunge off my face. It's been a mixture of flour and water, thick and viscous, and - as I've previously discovered - a devil to prize away from any body hair afterwards. Apparently it has a pedigree as the filling in the flans the comedians hurled at one another in the early Hollywood silent films. However, we've been told that most likely once we're working in the real world we'll be the victims of nothing more than harmless chemicals - or even only of soap lather - which shall be far easier to wash off, but here in college they're making us practice with flour-paste on the grounds that if we can cope with this we can bloody well cope with anything.)

I'm a little bit anxious to see the footage, but am assuming I've done okay; after all, taking pies in the face is the one thing I've been told I'm good at. It was volunteering as the stooge in the stocks at my school's annual fete in the summer of the previous year that had given me the idea of throwing in my decently paid job as a primary school teacher, and enrolling here to re-train - approaching thirty - as a clown.

That glorious hot day had been a revelation. Standing there on the playing field, I'd been the undisputed draw compared to the other stalls. Wearing just a pair of Speedos, my head protruding through a hole in the centre of the pillory that the caretaker had knocked up, the kids I'd been teaching during the week had approached me, giggling themselves silly - as well as their parents, and even a few of my colleagues on the staff - to lob plates of shaving foam at my face for 50p a go.

'Let us know when you've had enough, Rupert,' the headmaster had said, sidling up to me at one point, late on, concerned perhaps that I was overdoing it.

'I'm fine, thanks, Brian,' I'd said, unaware and unperturbed that I'd already endured more than three hours of this treatment.

Afterwards, in the shower, I'd felt fantastically buzzy, and over the next few months the feeling intensified: if I did nothing else in my life I wanted one try at being a slapstick performer. I badly needed to be watched while I got messed up. I knew there was a college in Harrow - The National Academy for Training in Slapstick Performance - which specialised. Of course it was crazy, but I'd just have to give it a try or I'd regret it forever.

So that's why, one midweek morning in the autumn of the following year, I was sitting in this nondescript rehearsal studio with the residue of paste in my beard, alongside a dozen other young men - my fellow freshers, most of whom were almost ten years my junior, all of us dressed in identical boiler suits - as I waited for the video to run.

It's always weird to see yourself in close-up, but there I am on the screen as I'd been just a minute or two beforehand, still clean, but - oh dear - looking much more nervous than I should have done, or had hoped I'd be. The pie - careening in from out of frame, right - whacks me in the face.

'Okay, let's freeze the tape,' Mark says. 'What's he done?'

'Shut his eyes too soon,' someone mutters.

'Blinked. Screwed his face up,' another student adds.

'Flinched,' a fellow class member disloyally pitches in.

There's no denying it, all of these observations are true.

'Yup,' Mark says, ruefully, '- he has.' He turns to me: 'Don't worry, uh ... sorry, what was your name?'

'Rupert.'

'Rupert. Yes, don't worry, Rupert - it's only your first try, and you'll soon get the hang of it. But you see, everybody - that was pretty much an object lesson in what you shouldn't do. Now I assume every one of you here in this room aspires to be a professional slapstick clown or stooge. If you succeed, people will have paid to watch you get hit with a pie. They're not going to want to see you scrunch your face up in anticipation. It looks amateurish. It's what they would do themselves if they were in your place. You're going to have to learn to suppress the natural instinct to protect yourself, and take that pie square on. Remember, always keep an open face. Yes, you can act dopey or gormless, or put on whatever expression your character requires, but it must not change. Not when the pie is coming at you.'

'Mark, sorry ...' one of my fellows interrupts, '- how do we stop the gunge from getting in our eyes?'

'Good question,' Mark replies. 'At the last second - at the very last nanosecond before the pie strikes - you may close your eyes. Leave it as late as you possibly can. Don't let the audience see you doing it. With practice - and you'll get as much practice as you want here in the college - you'll learn the timing. But listen, let's tell it like it is - no matter how good you are at judging the moment, quite often you're still going to get stuff in your eyes. It comes with the job. It's a professional hazard. No one says it's pleasant, but if you want to work as a slapstick performer you're going to have to deal with it.'

Once again they're trying to put the fear of God into us. Only a week ago us new-starters had been given an introductory talk by the charismatic college principal, Graham Weir. He didn't mince his words.

'Unless you're a bit of a masochist and exhibitionist,' he'd said, '- you're not going to thrive - either here in college or in the profession outside. Ideally, you should have an urge to be watched while you're undergoing treatment that may be uncomfortable and undignified.'

I'd had no doubt that this was exactly the impulse that was spurring me on.

The principal had made it plain that as slapstick performers, while consideration would always be made for our safety, no-one was ever going to bother too much about our comfort, let alone our dignity. The audience might find it amusing to watch us get covered in gunge, but for us on the receiving end there'd often be times when we'd be thoroughly wet through or genuinely cold or sticky, not to mention aching from physical exertion, and this would just be a part of our everyday job.

Back in the classroom, Mark has let the tape play on so to see how I'd behaved after the pie had hit me.

'Can anyone tell me what he's done now that he shouldn't?' he asks.

'Dropped his head forward,' someone ventures.

'Exactly.' Mark turns to me: 'Did you notice what you'd done there, Robert?'

'Rupert.'

'Sorry - Rupert. Now look,' Mark says, '- I'm not picking on you' (Although of course he is.) 'But you're going to have to learn - and everyone else here, too - never ever drop your head forward after you've been whacked in the face with a pie. Does anyone know why?'

'Because the audience can't see you,' the same student answers. I'm beginning to loathe this youth.

'Precisely,' Mark beams at him. 'It's a question of sight-lines. Keep your head up. If you don't, then all those above in the cheap seats won't have sight of what's happening to you. Remember, they'll have paid their money to watch you. They'll get a thrill out of seeing you being put through an experience they'd never dream of enduring themselves. They'll deserve to have an uninterrupted view of you with goo all over your face. Yes, of course it's your instinct to lean forward to let the stuff drop off, but you must resist that feeling. Always bear in mind it's not about your own enjoyment, or even about your comfort. The only objective is to entertain the public.'

Mark fixes us all with a meaningful stare, before breaking the spell. 'Okay, let's play more of the tape.'

It doesn't run for more than five seconds before I raise my hand. 'Oh fuck,' I say loudly, hoping to stave off criticism. They're not going to have to tell me what it was I'd done wrong next.

Mark looks at me. 'You've got a comment, Richard?' he asks.

'Rupert.'

'I'm sorry - Rupert.'

'Yes, I have, Mark,' I say. 'I shouldn't have wiped my face.'

'What does everybody else think?' Mark asks the class.' Should ... uh ... Rupert have wiped his face?'

There's an immediate, unanimous chorus:

'No.'

'No'.

'No. He should have left the gunge on.'

As if to compound my embarrassment, Mark rewinds the tape, and plays the sequence again. Way, way too soon, I'd scraped much of the gunk off my face with both hands, flicking it to the floor, and had tried to blink. I can see why this doesn't look good.

'So what should you have done, do you think?' Mark asks me.

'Not touched it.'

'Why?'

'So that the audience could see, erm ... the full effect.'

'The full effect of ...?'

'Of taking a pie in the face,' I say.

'That's right,' Mark says, before asking: 'And why did you wipe your face?'

'Instinct,' I reply. 'To get the paste out of my eyes as quickly as I could. And out of my nose and mouth.'

'And why did you want to do that?' our tutor interrogates.

'Because it was foul - nasty,' I admit, knowing it's an unacceptable answer as soon as I've said it.

Mark peers at me for a second or two, more in disappointment than reproach. It's an awkward moment, shaming. He's not a lot older than I am, but he's hugely experienced and intimidatingly fit. We students know that for several years he'd been a member of The Sewerats - the physical theatre company that puts on extraordinarily daring spectacles which place severe demands on their performers. A few weeks later our class is shown a DVD of their show Revolvers from about six or seven years ago, and Mark's in it. Wearing only a tiny, tight loincloth, he takes a tumble off a six metre high platform and splashes headfirst into a tank filled with black, oily mud. He's been a fearless slapstick stuntman.

'Okay, everybody,' he says now. 'Let's be absolutely clear. I'll reiterate what Graham said last week at the induction. You're here to train as slapstick clowns. To do this successfully you must trade in your right to comfort, and your right to dignity. Doing things that would be unpleasant or demeaning for most people is your stock-in-trade. If it's uncomfortable - tough. And I don't mean to single you out, uh ....'

'Rupert.'

'- Rupert, but if anyone here is anxious about merely taking a pie in the face then frankly you should think very carefully whether you're doing the right course, because hereon in it's only going to get more difficult.'

I take this as a warning, and over the coming weeks and terms I put in every effort I can never to betray a flicker of reluctance, no matter how taxing the activity is. Within a fortnight we'll be performing a simple, messy slapstick routine every day A aims a plate of custard at B, B ducks, C gets it in the face, et cetera, so that we become accustomed to regular, relentless messings-up. We'll spend almost as much time in the shower as in the classroom. There will be gymnastics classes to prepare us for physical comedy, training in the use of harnesses for aerial work, lessons on how to take falls like wrestlers, lectures from cold-endurance experts on the best tips for avoiding getting shivery once we're covered in gunk (it turns out there aren't any, except for keeping fit, and telling yourself not to mind - manning up, basically).

It certainly won't all be a breeze, such the day we rehearse a water-fight routine six times over, and I have to sit around in wet underwear despite suffering a nasty cold; or the time I get elbowed accidentally on the nose when we're practising mud-wrestling. But I work hard - very hard - and I never let go of my objective. I focus on the future when hopefully it will be me out there performing in a panto or the circus, taking that custard pie in the face, or maybe falling headlong into a bath of paint, in order just to make the crowd laugh, or - better still - to make some of them think: 'Eugh! How could he do that? That must be horrible!'

And if that's ever their thought, it'll be my laureate.