Blushing Lara laughed and looked nervous and uncomfortable at the racy question.
“Ummm, I mean, he, I just... I dunno, I don't think he knows if he's on linen or cotton or you know he just jumps...” she said.
She finished by saying: “If the bed's made every day it's good.”
Co-host Larry Emdur, 54, apologised to Lara for the risqué question: “Lara I apologise for Kylie's question, the interview was going so well right up until that point.”
“Just pushed a bit too far I think, crossed a line there, darl,” added Larry jokingly.
Kylie avoided being in hot water for too long as she replied: “Not at all, I'm sure Lara wanted me to ask that.”
While Lara responded with an awkward smile and crossed her arms.
The couple, especially Sam, 42, are known for being notoriously private.
Sam and Lara, who met in 2013, live in LA with their children Rocket, 4, and Racer, 2.