Come to find out, Kourt didn't exactly give sister Kim Kardashian the go-ahead to have the party at her place. In fact, she told her she couldn't, but while Kourtney was in New York filming Kourtney and Khloe Take the Hamptons, she received the evite for the party and saw that the "where" of the "who, what, where" actually listed her address.
In this clip from the upcoming episode, we see the moment Kourtney gets the evite and she realizes that someone obviously screwed up by sending it to her.
She thinks Kim actually thought she'd be able to do it without Kourtney finding out, which is pretty impossible given that every move they make is all over the internet. Plus, they posted pics from the party, so she obviously would have recognized her house.
For photos from the party (at Kourt's house) check out the gallery below.
This episode airs Sunday, November 16 at 9pm ET/PT on E!