Kim and Khloe Kardashian Grill Kourtney About Her Hickey in KUWTK Promo

Kourtney Kardashian should know by now that her sisters never let anything slip under their radar.

In a preview clip for Sunday's "Keeping Up with the Kardashians," Khloe and Kim grill their sister after she walked into the kitchen with an apparent hickey.

"Kourtney, what is this hickey?" Kim first asked in the video and Khloe added, "What is on your neck?"

The Poosh founder tried to brush it off and said, "My hair is here."

But Kourt's sisters didn't let her off the hook. "You have a hickey on your neck?" Khloe asked. "From who?" Kim further prodded, "Who on earth would you get a hickey from?"

Although Kim had joined in on the interrogation, it seemed that she might have known who did the deed all along.

"I think I know who it's from," she teased.

"Just let me live!" Kourtney told her sisters. "Don't analyze."

The mother of four opened up about her frustrations in a confessional.

"My sisters are pretty nosy when it comes to anything in my life," Kourtney said. "I don't know if they're bored in their own lives and they want to live through my wild dating life that they think is going on. Like, come on guys. Let's get it together."

As for who gave Kourtney the hickey, it looks like we'll have to wait until the new episode of "Keeping Up with the Kardashians," which airs Sunday night at 9 p.m. ET on E!

Got a story or a tip for us? Email TooFab editors at tips@toofab.com.