Sia's usually extremely private, keeping her face hidden behind wigs and hats.
But now she bared all in a tweet to get back a photographer.
The singer posted a nude photo of herself, saying she's been told someone was trying to sell naked photos of her online.
The Australian singer posted "Save your money, here it is for free. Everyday is Christmas!"
Someone is apparently trying to sell naked photos of me to my fans. Save your money, here it is for free. Everyday is Christmas! pic.twitter.com/aeQlnTwLuy— sia (@Sia) November 7, 2017
The photo shows the 41-year-old pictured naked from behind.
The tweet's also a reference to her upcoming album, which is called Everyday Is Christmas.