According to Internet legend, a cursed JPEG file circulates online, featuring an image of a dog with a much too human grin. If you happen to see this image, the dog will haunt your dreams, asking you to "spread the word" by showing its picture to someone else, thereby passing on the curse. The story of Smile.dog, which is the demon dog's name, is a so-called creepypasta – that is, a digital urban legend. Its curse is therefore a playful one, meant to be circulated as a hoax, but it is also a productive, yet challenging, place to ruminate upon ethics in an era of digital media. Through the lens of Jacques Derrida's concept of hauntology – a haunted ontology – this article explores what digital monsters and curses might teach us about ethics as a question of responding to that which haunts and hoaxes.