North West and Penelope Disick Make the Cutest Mermaid Princesses During Family Birthday Party By: MIKE VULPO Sat.

There's no birthday party like a Kardashian family birthday party! As the temperatures rose in Southern California Saturday afternoon, Kim Kardashian and Kourtney Kardashian decided to throw a joint-birthday party for their children North West and Penelope Disick. Let's just say the mermaid-themed celebration turned out to be oh-so-magical. As documented on Snapchat, the birthday girls dressed in matching mermaid outfits while Kim opted for the same costume as one of her emojis. Khloe Kardashian decided to wear lavender hair by her niece's request while Kylie Jenner was focused on showcasing the "Under the Sea" elements outside.