The socialite was photographed locking lips with actor Paul Iacono, who stars as a well-endowed teen in David Katzenberg's new TV project The Hard Times of RJ Berger.
A party guest says, "We thought it was a publicity stunt at first, but Paris was really making out with this guy."
And Paris, whose sister Nicky is Katzenberg's longtime girlfriend, has fuelled speculation that the young actor is her new man with a post on her Twitter.com blog.
She writes, "My new boy toy is hot," and links to a picture story about her night of passion with Iacono.
If the romance is for real, the young actor will be the socialite's first boyfriend since she split from reality TV star Doug Reinhardt in April (10).