The reality star revealed the gender of her third baby on the latest episode of "Kourtney & Khloe Take the Hamptons."
"Mason ran in here with the blue stick. There was a red star or a blue star," Kourt explained. The family then shared a home video filmed by Kim Kardashian, which showed footage from the moment they all found out.
While we're excited to see another Kardashian boy in the famous family, Mason wasn't thrilled about the sex of his new sibling.
"I wanted a girl," he admitted.
However, Khloe Kardashian was able to quickly change his attitude by pointing out, "Girls don't like aliens and Lego guys. When you have a brother you can say 'Look at all my Lego guys, brother.' You get to be rough and you can boss him around because you're the older one."
Kourtney has certainly embraced her third pregnancy, even showing off her bare baby bump in a naked photo shoot for DuJour.
"To me, nudity is not something to be ashamed of," she told the mag. "I'm at my best when I'm pregnant. It's such an amazing feeling, the transformation that your body goes through. There's something about that that's so empowering and beautiful, and I just really embrace it."