Selena Gomez and Justin Bieber have been on and off for a while now, ever since breaking up in January this year. At yesterday's Billboard Music Awards, the former couple were seated right next to each other, and they were also spotted kissing backstage.Taylor Swift, who also were backstage, had a very interesting reaction to their kiss. When she saw it, she turned her head around and looked disgusted.Click here to check it all out!