This Video of North West and Penelope Disick Speaking Their Own ‘Secret Language’ Is the Cutest Thing Ever

North West and Penelope Disick are the cutest BFFs.

To celebrate Kourtney Kardashian’s daughter’s fourth birthday, Kim shared an adorable video of North and Penelope speaking their own “secret language.” In it, the two young girls are seen standing on chairs and holding hands as they “speak” to one another in a language that isn’t English.

“Whatever secret language u girls speak, the way you girls protect each other & love each other is so special,” the reality star wrote on Instagram. “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!”

Kim isn’t the only Kardashian family member to wish Penelope happy birthday. Kourtney also posted a photo of her daughter in a mermaid costume, writing, “Happy birthday to my little mermaid! Seeing the magic in the world through your eyes makes me so happy.”

Even Khloé took to Instagram to wish her niece a happy birthday.

Check out the gallery above for North and Penelope’s cutest BFF moments!