For friend Anastasia "Stassie" Karanikolaou's 24th birthday party on June 8, the duo sported the chicest of looks with Kendall wearing a black and white patterned crop top and pants and Hailey choosing a black top and matching maxi skirt by designer Alex Perry and styled by Maeve Reilly. Naturally, Stassie's big night was a star-studded affair with guests including fellow model Winnie Harlow as well as makeup mogul Kylie Jenner. Taking to Instagram, the beauty mogul shared two videos of BFF Stassie, including one showing her blowing out the candles on massive white birthday cake inside a private dining room and another of Stassie dancing in front of their cars. The birthday girl – who shared the festivities with club promoter Zack Bia – stunned in a long sleeve, off-the-shoulder, semi-sheer silver sparkling dress. As Kylie wrote on her Instagram story, "The prettiest [two heart emojis] @stassiebaby."