Britney Spears stripped right down to tiny undies and gravity-defying shorts, even joking she's considering becoming a doctor while dancing the night away on Monday. The 39-year-old pop princess delivered another of her legendary home dances for her 27.1 million Instagram followers last night, throwing in mentions of the global pandemic and the fact that 2020 is wrapping up. The "Toxic" singer was dancing to Nelly Furtado's 2006 "Say It Right" track, and she was proving that at nearly 40, she's still got it. Check it out below.