If you can't come to Vegas, Britney will bring Vegas to you. Britney Spears opened the 2016 Billboard Music Awards with a medley of all the hits, choreography, and costumes currently on display at her Vegas residency. What a coincidence! She worked "Toxic," Slave 4 U," some deep cuts ("Breathe on Me!"), and twerked on a giant guitar. It's Britney, bitch.