Instagram / Kylie Jenner
The friends in question: The Jenner sisters' former private tutor-turned-friend, Tiffany Sorya, who turned 33 on Sunday, and Carter Gregory, who turned 26 and works for Capitol Records.
Sofia, Kylie and Kendall posted selfie videos of themselves getting ready together for the party, which was held at a nightclub.
"Wow, wow, wow!" Kylie, 21, shouted as she filmed Sofia, 20, showcasing a '60s style blonde hairstyle and a sparkling bra.
Kylie then shared a selfie video of her showing her wearing a blonde wig, a sparkling baby pink mini dress and sparkling rainbow platform wedges, standing with Kendall, 23, who sported a shimmering leopard-print dress and black sandals.