At just 17 years old, Billie Eilish is slowly taking over the music industry, and Britney Spears is taking notice. On Monday night, the 37-year-old pop star posted a nostalgic video on Instagram of herself dancing along to Billie's "Bad Guy." While the clip may seem like just another sexy dance video at first, upon closer inspection, it's actually the choreography from Britney's famous "I'm a Slave 4 U" performance at the 2001 MTV Video Music Awards. She even brought back the snake! What an icon! Of course, it didn't take very long for Billie to respond, as she simply commented, "omg." Yep, that pretty much sums it up!