On Friday, Madonna posited haunting cover of Britney Spears' 2003 hit "Toxic" to social media in honor of World AIDS Day and Spears' 36th birthday.

In this photo, Britney Spears and Madonna are seen performing at the 2003 MTV Video Music Awards at Radio City Music Hall on August 28, 2003, in New York City, New York.

Madonna Supports Britney Spears amid Conservatorship Battle: 'Give This Woman Her Life Back' "This is a violation of human rights! Britney, we coming to get you out of jail!" ...

In honor of World AIDS Day on Dec. 1, Madonna covered Britney Spears' "Toxic" on Instagram. She dedicated the song to both the cause and to Spears, since her birthday happens to be on Dec. 2.

Twenty years ago, the MTV Video Music Awards staged the Kiss Seen ‘Round the World, when Madonna, Britney Spears, and Christina Aguilera engaged in a three-way onstage makeout session during the ...