Whether it's a wedding, funeral or job interview, all of life's big moments seem to have a highly prescribed dress code attached to them, right down to the optimum number of buttonholes or correct colour of sockage.
All of them, that is, except Christmas, the one day of the year when nobody quite knows how to dress. "It's tricky," concedes Maggie Davis, shopping editor at Time Out. "You want to be comfortable and not worry about your jeans being too tight when you veg out in front of the TV, but then there's also this tremendous pressure to dress up."
Perhaps harking back to a time when most people would go to church to celebrate the birth of Jesus and sing hymns, the day still retains a strong sense of occasion. But given that most people don't actually leave the house on Christmas Day (or in the case of some, men in particular, don't even leave the living room), it seems a little pointless to wear anything formal. Surely a tracksuit or, for those of a fancier persuasion, a pair of cashmere pyjamas would suffice?
"Christmas Day should be all about relaxing, so anything with an elasticated waist-band is perfect," says Juliana Foster, author of The Christmas Book: How to Have the Best Christmas Ever. "I've never quite understood the need to dress up. After all, you've spent half the day cooking or pretending to like the gifts that you've been given why shouldn't you be allowed to take it a bit easy?"
For those foolhardy souls who have no choice but to leave the house, however, Foster has the following advice leave the novelty items at home. "It's kind of unavoidable but any item of clothing that makes a noise or lights up is a no-no," she says.
But aside from jumpers with appliqued snowmen and socks that play a tinny version of Rhianna's Umbrella, whether you're slobbing out at home or visiting friends, Foster suggests that 25 December should be a style free-for-all: "Treat it as the day fashion forgot," she says.
"You shouldn't bother with the normal social worries," concurs Davis. "Often I'll wear something I wouldn't be seen dead in on any other occasion. It can be quite liberating." This Christmas, Davis will be sporting "an old Eley Kishimoto jumper it's cream with red pompoms and so Christmassy that I can almost get away with it".
But what about the less inventive among us? "Christmas Day is a good opportunity to do some great family PR," reckons Davis. "It's the perfect moment to dig out that awful jumper your auntie gave you last year. Just smile politely and get it out of the way."
But fashioning your entire outfit from this year's gifts is tantamount to cheating. "It's not good etiquette to wear your presents there and then," adds Davis. "It's like walking out of the shop in new trainers."
For anyone still smarting from last year's surplus stash of fogeyish slippers and prickly socks, Angel Adoree offers a smart form of retaliation. Based in London's Brick Lane, her online company, Tshirtpatisserie.co.uk, lets individuals design their own Christmas T-shirts, which are then cutely boxed up, accompanied by a yuletide fairy cake.
Inevitably, the slogans that the T-shirts bear are not always so sweet. "We get endless numbers of people wanting to print rude things around this time of year," laughs Adoree. "We'll print pretty much anything people want, but the funnier ones are better. This year, we've had everything from 'Go Home: Christmas Is Cancelled' to 'Jesus Loves You. Shame Everyone Else Doesn't'."
And Adoree's favourite so far? "We had an older couple who came in to make an 'I Love Grime Music' T-shirt for their teen-age son. I don't think they knew what grime was, but the sentiment was there."
'The Christmas Book: How to Have the Best Christmas Ever' by Juliana Foster (Michael O'Mara, 9.99) is out now
Beauty spot: Four steps to freshening up before guests arrive
By Eliisa Makin
1. Open the bubbly
Sweet chestnut bubble bath, 10, from The Body Shop, tel: 01903 844 554: A festive scent
2. Brush up
Almond coconut milk scrub, 35, by Laura Mercier, from www.spacenk.co.uk: Nectar-sweet smell
3. Chill out
Bath oil, 28, by Miller Harris, www.millerharris.com: Take time for a therapeutic soak
Davana blossom shower gel, 25, by Molton Brown, www.moltonbrown.co.uk: An aphrodisiac lift