With a rubbery thunk, a tongue suddenly pokes out from a roughly gouged hole in the wall. It retreats back into the darkness just as rapidly. I consider letting it kiss me, but I doubt the New Museum in New York would allow it. Nearby, a crescent moon hangs in space on a length of fishing line. The moon is a croissant, and on it sits a butterfly. You could lean forward and take a bite, but it would spoil the effect. Usually I don't go around eating the art, much less snogging it. But there's plenty of food for thought in Urs Fischer's Marguerite de Ponty, an oddly titled exhibition (Marguerite was a pseudonym of symbolist French poet Stéphane Mallarmé) that fills the entirety of this space.  Fischer, a Swiss artist now living in New York, is the first to take over all three exhibition floors since the museum opened 18 months ago. The New Yorker has published a lengthy profile, and, whatever Fischer's talents, which are considerable, the exhibition itself is an ostentatious validation of the artist's increasing international stature.  The tongue and the croissant – Noisette (2009) and Cupadre (2009), to give them Fischer's titles – inhabit the second floor. The walls are clad in purple-rose wallpaper; one critic has called the effect "wrap-around Rothko", but I'll settle for puce. Fischer aimed a camera at the ceiling, adjusted the settings and took a snap of the spotlights. In the images that resulted, the white walls appeared this colour, so Fischer clad the gallery with it. He has also inserted a false ceiling, lowering the gallery height by two feet, and covered it with the photo of the original ceiling. Are you still with me? All this palaver was hugely expensive and time-consuming to arrange, though the installation, named Last Call Lascaux after the French caves filled with Paleolithic paintings, is little more than a puzzling bit of spatial tweaking.  The only other object in this otherwise empty space is a deformed grand piano. Fischer cast a real piano in latex, which was then held semi-upright with wires to stop it flopping on the floor. The object was then remade a second time, from aluminium. It looks like a badly erected tent, and makes you think of the Tom Waits song The Piano has Been Drinking.  A similarly tipsy effect is achieved on the lowest floor, where a couple of crutches sway pie-eyed, like drunks on the kerb. One legless crutch is doubling over: I imagine it throwing up in the gutter. The effect is amplified by the mirrored boxes that otherwise fill the gallery. Each has plain images of a single object silkscreened over the surfaces: a red London phone box, a shoe, the Empire State Building, lumps of cheese, cup-cakes, a candle, a cigarette lighter, a pear. I struggle with what it all might mean. The minimalist mirrored box meets the excesses of consumerism? Italian artist Michelangelo Pistoletto did much better things with silk screen figures stencilled on to mirrors in the 1960s. Give me the rougher, blunter Fischer any day, instead of this smooth operator, purveyor of shiny things to magpie-like collectors.  Comparisons may be odious, but Fischer's art betrays all kinds of influences and careless correspondences. A pink cast of a Beaux-Arts ornamental street lamp has gone all droopy, like a wilting guest at a Salvador Dali theme night. It reminds me of Martin Kippenberger's wonky streetlights, but they were funny. This is just rhetorical. Kippenberger's tempestuous spirit is one of several hanging over Fischer's work. In 2007 Fischer had a crew excavate a hole, eight feet deep, beneath the ground floor of Gavin Brown's New York gallery, while deliberately omitting to inform the landlord. He called the work You. It was a sort of grave; a belated continuation of an already familiar artistic gambit, but audacious and raw. Fischer has also cast heads in the manner of Bruce Nauman, and perpetrated a bewildering variety of works in his career, which began in the mid-90s. Some of what Fischer does may be unoriginal, but unoriginality is something all artists have to deal with. His art has always had a lot of spirit, even when he reprises the familiar.  Then, suddenly, you come across a work that is both magical and confusing: a cake hovering in mid-air, without aid of strings or any visible means of support. It is a stupid cake, round and dumb with cheap pink icing and piped-on decorations. It is suspended above a New York subway seat that has been screwed to the gallery wall, and is kept aloft by a powerful magnet hidden in a sports bag that's also stuck to the wall. The cake only manages to stay airborne by being placed, to the precise millimetre, in the magnetic field.  Much less convincing are the massive metallic blobs and lumps that share the top-floor gallery with the cake. Blown up from little bits of modelling clay that the artist has pummelled and twisted, they were then fabricated from a greyish aluminium in China, and flown back to the US. All this seems a lot of effort for sculptures that could be the beginnings of something, or the end of it, but which do little more than take up a great deal of space. Some are as big as a truck. They have been compared by critics to Willem de Kooning's figurative sculptures of the 1960s, which began hand-sized before being hugely enlarged. But the comparison to De Kooning is as overblown as Fischer's leaden behemoths, whose production leaves a trudging carbon footprint, and whose overall effects are null. But maybe he wanted them to be inert. It is a pity: one of the qualities of Fischer's art is its liveliness.  A week ago, during a series of talks in Toronto focussing on the current financial crisis and how it affects art, the New Museum's Richard Flood told the audience that the days of artistic mega-projects were over. Successful artists were no longer routinely getting $50,000 monthly stipends, Flood said, and huge installations costing the earth were no longer viable or desirable in these straightened, austere times. Fischer's show seems oblivious to the trend. Many of Fischer's works over the years have displayed a make-do-and-mend, hand-made, bricolage approach, but this exhibition is like a variety act who has suddenly hit the big time. The gags are much the same, but the stage is bigger and more daunting. The New Museum's remit is to show younger artists, few of whom will now be able to compete with the production values of artists like Fischer. Some time soon, he may not be able to compete with himself.  But wait. In a back stairwell are some little collaborative pieces Fischer made with the terrific, underrated German artist Georg Herold. The sculptures – if you can call them that – are wonderfully ridiculous: short light fittings whose fluorescent tubes have been replaced by a cucumber and a carrot, held in place with rubber bands. These may just be jokes, but they have wit and sculptural ingenuity. Next to these are some little plaster casts of thumbs and fingers, grasping a real frankfurter. To make things this direct, this dumb, this disarming and this funny takes talent, gall and nerve. What does it add up to, you ask. Perhaps nothing more than a loud guffaw, echoing up the building from the stairs.
The Swiss artist's edible moons, flying cakes and drunken pianos fill the New Museum in New York. But haven't we seen them somewhere before?