It's her party - and she'll sue for $15 million if she wants to.
A mysterious, self-styled, Park Avenue socialite filed suit in Manhattan Supreme Court for the whopping wad of cash charging her free birthday bash at a trendy Chelsea nightspot was such a bust it caused her "embarrassment and anxiety."
Lucia Kaiser claims in court papers the shindig she threw this past Dec. 4 for hundreds of her closest pals at Club Ohm was so poor that "many guests left the ... party and [she] suffered great loss of esteem in the community."
Among other problems, she said, the West 22nd Street club's cascading fountain wasn't working, there wasn't enough security and there were no free hors d'oeuvres.
A spokesman for the club, R. Couri Hay - who called the suit "one of the silliest things I've ever heard" - admitted the fountain wasn't working, but said there was "excessive security" and that the hors d'oeuvres - and just about everything else - were free.
He also accused Kaiser of doing the hustle.
"She conned us. She bills herself as a society girl. She promised all these celebrities were going to come - Madonna, the mayor, the police commissioner, Cher, and she said Diana Ross was going to sing," Hay said.
The club took her at her word, Hay said, and waived the $20 entrance fee for her guests and provided her with a DJ, 14 cases of champagne and mixed drinks, a birthday cake and appetizers - all free of charge.
"She got a fabulous free birthday party [and] she didn't even tip," Hay said.
Two celebs did show up - Harry Belafonte and Quincy Jones. But a spokesman for Jones said he wasn't sure the superstar producer actually knew Kaiser.
"He might have just shown up there because it's a hot club," he said.
Kaiser told the club she was expecting 1,200 guests, but only 500 came, said the president of the club, Jerry Levy.
He said the 50-ish woman was brought into the party "on a couch with people throwing rose petals at her. They were holding her up like in the Roman days."
Levy, whose club has become one of the city's hottest nightspots by drawing celebs such as Robert De Niro, said the suit left him "totally baffled."
"It was a marvelous party," he said. "When [Kaiser] left, she hugged and kissed me and said, 'Thank you so much.'"
Hay said Kaiser isn't welcome back at the club.
"The only thing she deserves is a free spanking," he said.
Kaiser couldn't be reached, and the Park Avenue address she gave on the court papers appears to be non-existent.
Her lawyer, Stephen Kennedy, is out of town and couldn't be reached, his office said.