This animation consists of a few frames from the 1977 Japanese horror movie House (or Hausu). According to Wikipedia, the movie features seven high school girls being devoured in various ways by their aunt’s country home. The movie is available on YouTube, and the scene from which this animation is taken shows a girl being devoured by a piano. The scene begins at about the 1:02:30 mark.
Image provenance by Bacchus at Erosblog.