Leading the way, Gigi herself wore a white crop top, jeans, and a denim jacket. Her perfect denim-on-denim look was inspired by Britney Spears and Justin Timberlake at the 2001 American Music Awards. Hadid’s party started off with a festive cake with a gigantic sparkler in the middle and also included sing-alongs, extravagant-looking sliders, and more. Sounds like the best birthday party ever, doesn’t it?