10/30/2011 at 05:30 PM EDT
Where's Batman when you need him?
channeled her inner villainess at the New York club Lavo on Saturday night, slipping into a green bodysuit and red wig as Batman bad girl Poison Ivy at a Midori-sponsored party.
Not at the party: Kardashian's husband of nine weeks, pro basketball player Kris Humphries.
"I'm going to Australia tomorrow so I'm in New York alone tonight," the reality mogul, 31, told PEOPLE, brushing off rumors
of trouble in her marriage.
"Something I really prepared Kris for [was] to let him know that no matter what we do, there's going to be rumors," she said. "It used to really upset me and now I don't even think about it."
The couple are facing another challenge: TMZ reports
that Humphries, 26, believes he was bilked out of hundreds of thousands of dollars by Boston hedge fund manager Andrey C. Hicks, a guest at the couple's wedding extravaganza
in August. Hicks was arrested last week.
Kardashian wouldn't discuss the matter. A rep for her husband says, "Kris Humphries is a victim of an investment fraud. He is working with law enforcement authorities and will not have any further comment until the matter is resolved."