The 34-year-old reality TV star is facing a lawsuit from model Michael Girgenti, who claims he had unprotected sex with her after they met on a photo-shoot in August 2008 and filed paperwork at Los Angeles County Superior Court this week in a bid to get joint custody of her three-year-old child, Mason.
But the 'Keeping Up with the Kardashians' star insists there is no way Michael is Mason's real dad, as they never had sex.
A source close to Kourtney told gossip website RadarOnline.com: ''She did not have sex with that model. This whole thing is so ridiculous. She thinks it is stupid and it really isn't true.''
The insider added: ''Kourtney knows who the father of her son is and it isn't this guy.''
Michael wants the judge to order DNA tests for Kourtney, Mason and her long-term boyfriend, Scott, 30.
Scott also has a 13-month-old daughter, Penelope, with Kourtney.
A hearing has been set for next month.
The couple has yet to comment on the allegations but were spotted looking miserable on a dinner date at Mr. Chow in Malibu on Friday night (09.08.13).
The actress thinks it would be tough to recast her character, Winifred Sanderson.
Beck wishes he'd had ''more fun'' when Kanye West invaded the stage in protest at his 2015 Grammy Awards win.
The Duffer Brothers wanted to "experiment a little bit".