Penelope Birthday: Kim Kardashian shares video of North and Penelope holding hands and dancing

Kim Kardashian has shared a very cute video of North and her BFF Penelope speaking their own "secret language".
The proud mum wished Kourtney and Scott's little girl a happy birthday alongside the clip, and gushed about their special bond.

In the minute-long video, a very smiley North and P are holding hands and dancing while excitedly saying something completely incomprehensible to one another.
"Whatever secret language you girls speak, the way you girls protect each other & love each other is so special," Kim wrote.
"Penelope, North is so lucky to have a best friend like you! Happy Birthday my sweet P. I love you to the moon and back!"

Whatever secret language u girls speak, the way you girls protect each other & love each other is so special. Penelope, North is so lucky to have a best friend like you! Happy Birthday my sweet P. I love you to the moon and back!

A video posted by Kim Kardashian West (@kimkardashian) on Jul 8, 2016 at 8:29pm PDT

Khloe also took to social media to share a sweet message for her niece alongside a picture of the reality star dressed as a mermaid.
"Happy birthday my sweet Penelope!!! May you believe in mermaids for the rest of your life! Like your aunty does."

Happy birthday my sweet Penelope!!! May you believe in mermaids for the rest of your life! Like your aunty does 💜💜💜

A photo posted by Khloé (@khloekardashian) on Jul 8, 2016 at 6:41pm PDT

While grandmother Kris said: "Happy birthday to our little princess, my sweet angel girl Penelope!!!!
"You bring so much joy to our lives and I love you more than words could ever say!!"

Happy birthday to our little princess, my sweet angel girl Penelope!!!! You bring so much joy to our lives and I love you more than words could ever say!! #sweetgirl #happybirthdaypenelope #myheart

A photo posted by Kris Jenner (@krisjenner) on Jul 8, 2016 at 6:27am PDT

And doting mum Kourtney wrote: "Happy birthday to my little mermaid! Seeing the magic in the world through your eyes makes me so happy."
Happy birthday, Penelope!

Happy birthday to my little mermaid! Seeing the magic in the world through your eyes makes me so happy.

A photo posted by Kourtney Kardashian (@kourtneykardash) on Jul 8, 2016 at 7:21am PDT