Leather sleeves bolted on to an otherwise simple T-shirt? Ruching where you'd least expect it? A strip of French lace running down the spine of a day dress for no apparent reason? A random panel stitched on to a jacket to create a 3D effect? New season cool is all about finding strange and interesting little surprises in your clothing.
Why does Christopher Kane's black leather pencil skirt feature a print of crocheted squares? Or perhaps even more baffling, why are his little black dresses held in place by straps filled with fluorescent gel that changes colour with body heat, fizzing and bubbling like a lava lamp?
"Why?" is the new black. If you see something ingenious going on in a garment but are puzzled by its function, don't be. You've simply stumbled on to the latest fashion look. Given the wobbly economic climate, it makes sense that we are starting to see clothes bristling with novelty. After all, haven't we all got enough pairs of standard jeans? Think of it like coming across a puzzlingly beautiful line in a favourite poem, or an unexpected key change in a piece of classical music.
During the Paris haute couture season, the term being bandied around to describe this sort of design-infused piece was "obscure couture"; fashion creations that posed a question but which looked so polished, sophisticated and glamorous that no one cared too much about the answer. This is clothing that makes other stuff in your wardrobe jealous.
Last week, I styled a fashion shoot featuring dresses packed with a bewildering amount of design detail. One Prada number had several prints - windowpane, snake and spot - and four colours not including the base; eight large buttons (purely for decoration); box and fine pleats; a Beatnik belt and fussy yolk-style collar. Strangely, it worked.
Another Celine 1960s-feel shift had a body-skimming torso with off-centre panelling that jutted out, transforming it into something radically new.
After a summer of wafting cottons and silks, it's refreshing to be reacquainted with attention-grabbing fabrics, from panne velvets to "touchy feely" textiles often worn in layers to offset sheer with opaque, or glossy with matte. Trends are no longer simply about a particular length or shape, but more a tactile surface or unexpected pièce de résistance on a timeless shape.
Prada's Perspex wet-look giant sequin paillette scales, for instance, make an otherwise classic pencil skirt look as though it had been ripped off the tail of a passing mermaid.
Behind many complicated patterns inspired by sources as varied as Fabergé eggs and Qing Dynasty ceramics lie simple silhouettes. But there are some surprises, too. The modernist sculptors Barbara Hepworth and Henry Moore inspired Burberry's strange, supersized cocoon jackets.
What has caused the fashion scales to tip to excess rather than to the other extreme, simplicity? Besides the global recession, Lady Gaga may have something to do with it.
Gaga's dramatic diva style, which advocates the wearing of preposterous heels and full (stage) make-up at all times, has triggered a backlash against the just-throw-it-on-with-no-make-up look of "it" girls such as Alexa Chung.
I'm no fan of Gaga, but all credit to her for putting forward a case for women to stop wearing vintage/grunge/festi chic and get high fashion back to being what it was: something to gawp and wonder at. The Gaga effect sees sensational (literally) outfits for day as well as evening wear, which have the power to transform the wearer. And when it takes just one item, be it a dazzling pair of shoes or boots, a fantastic power jacket or a dress in an ingenious fabric to do this, it's a good thing. Expensive clothes should work for their keep.
Watch out for more examples in designer advertising campaigns, which traditionally pinpoint the mood of the moment. Burberry plonks fur flat caps with country tweeds and the model Freja Beha Erichsen dons a bouclé jacket with an assortment of strange headpieces, including Mickey Mouse ears and a tweed visor, in Chanel.
But it's the combination of the trailblazing designer Marc Jacobs and the art house photographer Juergen Teller that nails the essence of the new season.
Images of the quirky actress Helena Bonham Carter, strangely distorted, wearing a scaly, sequinned dress and spotty tights, poses the biggest "why?" of all. Best not to ask. Just wear it.