Gigi Hadid was a guest at “The Tonight Show Starring Jimmy Fallon,” and revealed a bit of her friendship with Serena Williams, including the fact that she’s a ‘karaoke legend.’Gigi Hadid and Bella Hadid look unrecognizable with shaved heads and blunt-cut bangsGigi Hadid just revealed she’s launching her own fashion lineFallon showed her a photo of herself at the U.S. Open, where Hadid is screaming in excitement. When looking at the photo, she said, “That’s like the most Serena expression ever.