Around 20 celebrities, including actress Jennifer Lawrence, had images of themselves taking leaks posted on image posting website 4Chan.
Mary Elizabeth Winstead (whoever she is) said the images of her were old - and were snapped when she was taking a piss outside a New York bar.
The user posting them - who defined him or herself as a "collector" rather than "hacker" - said more images of different celebrities urinating would soon be posted.
While some of the celebrities said the images were fake, others have confirmed their authenticity.
Actress Winstead posted on Twitter (of course she did): "To those of you looking at photos of me crouching down like a humbled dog outside a bar in NYC - my husband took this photo years ago - their was a MASSIVE line for the bathroom and I couldn't hold it in.
The FBI has investigated previous photos of celebrity leaks, including leaks involving Scarlett Johansson, Mila Kunis, Christina Aguilera and footage of television sports reporter Erin Andrews pissing all over a Tennessee homeless man.