Not anatomically, you understand, anyone with access to a contraband Key Stage 2 biology textbook or Sister Wendy's Book of Crumbling Old Statues having grasped the crucial differences after a few short years on the planet, but socially.

No matter how advanced their exposure to Gok Wan and exfoliants in recent times, men will always be left clutching at their temples like the Confused.com logo when presented with the time-old riddle, "Why do girls go to the loo together?"

Are we monitoring our levels of hydration by comparing urine samples with each other and consulting a Dulux colour chart (Tuscan Sun, Tracy? Lay off the Special Brew for an hour, eh?).

Musicals

Do we stage amateur productions of Gilbert and Sullivan operettas for an exclusive audience of bathroom attendants and hand-driers, in between our rounds of cheeky Vimtos?

Is it because our teeny weeny Going Out Bags, attractively useful though they might be as armpit-warmers, can only actually accommodate £2.50 and a super-plus tampon, thus meaning we have to pool one set of girlish accoutrements across the four bags of our collective group and then march off to use them all together?

Are we grouting the tiles? Doing yoga?

Recycling the paper towels into decorative papier-mâché salad bowls?

Rave review

While I would sincerely love to do a bit of positive PR for my gender and tell you the above are all true (my performance in The Mikado at Holloway Wetherspoons got a rave in Time Out), I also feel it's my duty to expose the real reason as the anti-climax it is: we're talking about hair.

That's it.

When girls go to loo in groups, it's so we can talk about hair.

I can feel Emeline Pankhurst turning in her grave as I type this, but the fact stands.

Hair.

Always hair.

Bounce

Go to an international conference of the world's top female neurobiologists, and the toilets will be full of phds complaining about their lack of bounce and lustre.

"I'm thinking about lowlights," one will be saying, "but I worry they'd make me look washed out against the white coat…"

But the gaggle of gal pals (or "waggle", if I'm using the Sunday Times Magazine as my source of popular slang) are just taken along as a starting point, the home front, because what we really want to do is meet strangers in the loos and talk to them.

About hair.

Bonding

This is female bonding at its most primal, from whence deep, meaningful, sometimes seven-minute friendships are born.

On Friday night I became so embroiled in a hair discussion with drunk ladies A and B in the loos of a cocktail bar in Angel that my flatmate was sent to extract me, concerned I might have been drugged or talked into pyramid selling.

"Is your hair real?" squeaked Drunk Lady A.

"It looks so perfect I thought it was a wig."

"Why thank you, kind lady, it is indeed real.

"As far as hair bleached beyond all colours known to nature and backcombed for several hours until it reaches the texture of wicker matting and the look of a Playmobil figure can be real, anyway.

Relish

"Your hair, too, is very, um, nice," I reply with the practiced art of one who relishes hair-based bonding.

Hair based-bonding proves too literal a term as Drunk Lady B then shows me her glued-on extensions and insists I touch them.

"How nice and gluey. Are those highlights or a bit of spilled White Russian?", and so on it goes.

When, after seven minutes, my new waggle are showing no signs of running out of follicle-chat and I still haven't escaped to have a wee, I suggest a rousing chorus of H.M.S. Pinafore and leg it while Drunk Lady B decides to be sick.

Important

Looking back as I leave, it is heartwarming to see the spirit of girlhood alive and well in the face of adversity — Drunk Lady A is holding her hair back for her.

She understands what's important.

* ITV Play is the closest we've come in recent years to a quasi-philosophical problem along the same lines as Schrödinger's cat.

If a caller actually guesses an answer right, but you are not there, up in your living room at 4am rocking back and forth quietly muttering to yourself, to observe it, do they really win anything?

This is the beautiful, evil, brilliance of ITV Play — the unshakeable knowledge that the moment you turn off the TV will be the moment all the answers you've been compiling for four hours straight will be revealed, and you will know you're a genius.

But you can never turn it off, so they will never be announced, and you will never know.

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