Mine is a generation of men that was defined by its underpants. We prized them for their garish styles and loud colours; and because they annoyed our baffled parents, still shell-shocked from the second world war; and because they told people – teachers, the police, girls – who we were. It is painful for men like us to accept, finally, that for our sons and our grandsons, underpants are unimportant, disposable products, designed to be worn once, ruined by shallow enjoyments, and then flung away filthy in the lane. It's hard for us to let go of our underpants. But the fact remains, the nonagenarian high-street giant HMP is in receivership as of last Monday and going down with it is everything we held dear.

The great and the good of a certain age let out their lamentations. The personality David Hepworth edited a succession of populist underpant magazines in the 80s, 90s and 00s, aimed at everyone from young, confused boys to elderly uncertain men. In Tuesday's Independent newspaper, Hepworth was hurriedly promised a gift voucher in exchange for remembering working at a branch of HMP in the 70s: "The queues for the tills stretched to the end of the queues," offered David, nostalgically. "In the 80s and 90s, when an underpant could be sold for more than £8, they were even longer. The only thing that men under 30 wanted was an underpant." Fine words, David. But, as Sir Kenneth Clark said in the opening of TV's Civilisation, fine words butter no parsnips. So what happened?

My showbiz friend the Hollywood film writer Peter Baynham, whose latest film features Adam Sandler as a Dracula, spoke morbidly of being a teenager in Cardiff in the 70s. He claimed he would visit Cardiff's famous independent underpant store, Spillers, each Saturday and spend his paper-round money on a colourful and up-to-the-minute underpant.

Then he would walk defiantly through Splott with the elasticated tummy band pulled dangerously high up out of his trousers to the mid-point of his torso, his underpant serving as a siren shriek to lure likeminded Splott (and Canton) youths into his orbit. But today's young people have Facespace and The Twitters to enable them to seek out soulmates. The day of the underpant as an essential badge of self-identification and an oiled funnel of adolescent social lubrication is long gone, a change HMP were sadly and fatally slow in anticipating.

For more than nine decades, the HMP logo, of a little dog burying a stolen pair of underpants in a dark wood, has been one of the world's most recognisable brands. But no more. I personally have taken quite a heavy financial hit from the collapse of HMP. I am a standup comedian and in 2004 I pioneered the now commonplace idea that comedians should sell bespoke souvenir underpants. My management company at the time pooh-poohed my pants and it fell to a Cardiff-based independent Go Faster Stripe to make a sideways move from making and selling novelty babygrows to marketing my Stewart Lee underpants online.

I have since shamed all other standups worldwide, including your new god Louis CK, by designing and producing an entirely new line of quality underpants every year, to the delight of broadsheet underpant critics and my loyal fanbase of underpant-wearing pseudo-intellectuals. Eight years since my old management dissed my pants, I had, for the first time, convinced HMP to provide me with a high street point of sale, and more than 30% of sales of the new carpet-textured underpant I launched last November had been over the counter of the ailing underpant giant. But now I will never see the money from those sales, my profits and my Chinese labour costs swallowed up by HMP's debts, my break-even point receding into the distance.

Without HMP, there is now no competition for tax-evading online underpant outlets, or for supermarket underpant retailers, who buy cheap underpants and sell them at a loss to entice shoppers in. This won't affect makers of pointless underpants adorned with the face of Michael McIntyre, a joke about cockerels, or a picture of The Stig, but makers of inherently worthwhile and clever underpants like mine will find it increasingly hard to operate cost-effectively. Big retailers will drive down the prices they'll pay suppliers per underpant, as surely as they have done with pints of milk. Pantufacturers have artificially propped up HMP for the past few years to avoid this Ballardian dystopia. And what did you do? Nothing.

The Twitters internet website was alive, on Tuesday, with opinion on HMP's demise. The Covent Garden musical theatre shop Dress Circle loomed up, like a terrible all-singing, all-dancing Aztec God of Death with the face of Sheridan Smith, to remind the music theatre community that it was "still open for all your disco pant needs". Sir Alan Sugar, anxious to maintain the illusion that he has some kind of insight, said he saw HMP's collapse coming two years ago (and yet he had been unable to foresee the immediate obsolescence of his own Amstrad GX4000 games console). And the rap-singer Professor Green, who is a professor of nothing, identified the abstract dimension to HMP's woes thus, writing: "We may as well give up on any medium that involves physical matter." Despite his lack of any real scientific qualifications, Green is on to something.

Like the visionary mystic Sir Alan Sugar, I too saw this coming. A decade ago, while in British Columbia researching an idea for a comedy character, I attended an internet industry conference in Chilliwack, the ground zero of Canada's own mushrooming silicon valley. A young internet entrepreneur did a presentation recommending the then unheard-of idea of virtual underpants. The virtual underpant was of course much cheaper to produce than its real-world counterpart, because it did not exist and remained legally the possession of the supplier after purchase.

To me, it appeared that the speaker was naked and yet my nerdy neighbour reassured me that the man was wearing a pair of the virtual pants, for promotional purposes, and that perhaps I wasn't "techno-savvy" enough to see them. "Besides," he said, without an ounce of sentimentality, "isn't it a drag how much goddam space jockeys take up in your apartment, eh?"

I pulled my underpants up above my trousers by the elasticated bellyband and invited him to stroke the cotton weave. The disdainful look on his face showed me that we were already doomed.

Stewart Lee is curating The Alternative Comedy Experience for Comedy Central, from 5 February. His latest DVD, Carpet Remnant World, is now 35% less easily available than it was a week ago.