Hundreds of guests -- including Paris Hilton, Lindsay Lohan, Yoko Ono and a host of big-name New York fashion designers and models -- had been asked to turn up Thursday night with full-on head accessories, or at least a party mask.
"In the spirit of Gaga's nostalgic aesthetic, we inspire you to honor her dedication to this fragrance and celebrate your shared passion for fashion," the invitation card said.
Upon arrival, invitees were greeted by muscular young bare-chested male models in skin-tight leather jeans, as well as black-tinted hors d'oeuvres and fuming blood-red margaritas -- all hints of things to come.
Onto a giant screen affixed to the Guggenheim's famous spiral gallery appeared New York photographer Steven Klein's five-minute film to promote Fame, which is billed as the world's first eau de parfum that is black in color.
Most definitely NSFW -- Twitterese for not safe for viewing at work -- it cast the chart-topping singer-songwriter as a latex-clad Gulliver in a "Metropolis" bondage nightmare, her naked body overrun by, well, muscular male models.
"You know, the film was expensive," Klein told the Hollywood Reporter amid talk that it cost more than $1 million to make, "but I guess the film has a price, fame has a price, the fragrance has a price. Everything has a price."
Finally, Gaga herself appeared, inside the darkened bottle replica, seemingly asleep on a velvet day bed, wrapped in a black fur stole, as Edith Piaf ballads filled the vastness of the Guggenheim's atrium.
It took a few minutes before the adult guests -- no children or teenagers, despite the demographics of Gaga's fan base -- realized they could step up, stick their hand through a hole and actually touch a real-life celebrity.
"Touch Lady Gaga's hand, but please don't wake her," read instructions helpfully printed over the opening, and touch her many did, reaching deep inside for her left hand with a peace tattoo under the wrist.
"Her fingers were cool to the touch," one guest, Karen Menge, sporting a purple silk hat, told AFP. "Even though she seemed to be in an unconscious state, you felt that somehow you were communicating with her."
More to the point, a young woman who identified herself only as Meredith, and employed a nickname Gaga fans use for their idol, said: "Everybody wants a piece of Mother Monster."
This went on for more than an hour, before Gaga woke up to the tune of David Bowie's "Fame" and under the constant gaze of live remote-controlled television cameras with ultra-wide-angle lenses that made her look chubby.
That's when Hollywood tattoo guru Mark Mahoney and assistant Wes Brown got to work, painstakingly adding to Gaga's already substantial collection of body art, using the shaven back of her head as their canvas.
"It's kind of a Renaissance era cherub, a nod to her Italian heritage," Mahoney -- who also did Gaga's "little monsters" left-arm tattoo the day after she collected two Grammy awards in 2010 -- told AFP afterwards.
Asked what it was like to work in such public view, Mahoney -- who got his start in his craft about 35 years ago, tattooing motorcycle outlaws in his native Massachusetts -- said: "It was a little distracting at first."
Not only were there all those people milling around the museum, he said, but inside the "bottle" were Gaga's sister, her hair stylist and a few other people, making for an extremely crowded working space.
"But once I got the pattern on, I realized it was just a perfect image for that place on the body," Mahoney said. "I knew it was going to be fine, just because it seemed to fit so perfectly right there."
Mahoney worked slowly and painstakingly, pausing whenever Gaga took a swig of Veuve Clicquot straight out of the bottle, puffed on an electronic cigarette or playfully let her pals plant lipstick traces onto her breasts.
But the timing was impeccable. By the time the job was done, a few minutes after 11 pm, the open bar was packing up and the ushers began shooing the last remaining guests out onto Fifth Avenue.
"We've got to prepare for regular business tomorrow," one usher explained, as Gaga -- who never publicly uttered a word, let along sang, all evening -- disappeared with her entourage into the night.
-------------------------------------------------------------------------------------------