Kourtney Kardashian's adorable son Mason celebrated his fifth birthday over the weekend, and the family all dressed up as characters from The Nightmare Before Christmas at the party! Well, MOST of them.

Khloe shared some spooky snapshots on Instagram and wrote, "Kourtney pulled a "mean girl" move on me and had me dress like Sally from The Nightmare Before Christmas," adding that "everyone else was mad chill. lol thanks @kourtneykardash #MasonsBirthdayBash."

The Kardashian family's makeup artist Joyce Bonelli painted the ladies' faces, and while Kendall didn't go as crazy as Khloe with the theme, Kylie seemed to think she was exempt from showing up in a costume. Some nerve!

And speaking of makeup and the Kardashians, yesterday it was announced that supermodel-in-training Kendall is the new face of Estee Lauder! She turned 19 less than two weeks ago, so talk about a great belated birthday gift!

"Here comes the big news," Kendall tweeted on Saturday. "It's w/ me and @esteelauder - and @voguemagazine has all the deets. I am super excited to announce that I am the new face of @esteelauder!!" Check out the video below -- and congrats to one of our fav members of the Kardashian household!