A photo posted by Khloé (@khloekardashian) on Nov 11, 2014 at 4:24pm PST

What's this? What's this? On Saturday, Nov. 15, little Mason Disick got the coolest birthday party a (currently) 4-year-old could ask for. The son of Kourtney Kardashian and Scott Disick had a Nightmare Before Christmas-themed bash, and in signature Kardashian style, the family went all out! 

Mason's proud, pregnant-again mom posted a picture of a giant Jack Skeleton doll leaning against the column in what appears to be grandma Kris Jenner's Calabasas mansion next to a Christmas tree covered in cobwebs. 

"'Twas the nightmare before Christmas…" Kourt, 35, captioned the photo. 

And while mom kicked things up a notch in the decorations department, it was Mason's aunt Khloe Kardashian who really got into character from Tim Burton's spooky and beloved 1993 stop-motion animated film for her nephew's party. 

"Kourtney pulled a 'mean girl' move on me and had me dress like Sally from The Nightmare Before Christmas while everyone else was mad chill. lol thanks @kourtneykardash #MasonsBirthdayBash," Khloe, 30, captioned a photo of her in full costume with her half-sister Kylie Jenner posing next to her. 

A photo posted by Khloé (@khloekardashian) on Nov 11, 2014 at 5:32pm PST

With another little one on the way, Kourtney threw the get together a month before Mason's actual birthday (which is on Dec. 14), and had his pals get dressed and dolled up for the occasion. 

Makeup artist and family friend Joyce Bonelli dolled up the girls and the little ones (including her own son Zeppelin, who posed in a picture with a little girl who appears to be Kourtney's youngest, Penelope, 2). 

A photo posted by Khloé (@khloekardashian) on Nov 11, 2014 at 7:21pm PST

Though she didn't get the head-to-toe treatment like Khloe, model Kendall Jenner also sported some makeup for the bash. The only sister not in attendance — Kim Kardashian, who is currently traveling in Australia. 

"Just touched down in Australia!!! My perfume world tour begins for my new fragrance Fleur Fatale! Next stop India then Dubai! All in 1 week!" she tweeted on Nov. 15. "Missing my baby girl so bad already! Was going to bring her but 3 countries in a week is too much traveling. Daddy time will be much better."

Tell Us: What do you think of Mason's party?

scary-go-round. Mason knows how to throw a good party ????????

A photo posted by Kendall Jenner (@kendalljenner) on Nov 11, 2014 at 8:50am PST