Smile Dog, also known as Smile.Dog and Smile.jpg, is the titular character from a chain letter {{creepypasta}} of the same name. It is rumored that the original image causes paranoia and insanity from viewing it, and when the viewer goes to sleep, the dog haunts them in their dreams. Sharing the image with someone else, that is “spreading the word”, is the only way to reverse this. If this is not done in three days, the picture will distort to show a scarier version of itself, causing even worse nightmares for the viewer. Neither the original image nor original distorted version can be found on the internet.
Pictures of Smile Dog usually show it with a {{grin}} that reveals its humanlike {{teeth}}, and sometimes has {{blood}} dripping from it's mouth. The distorted image is tinted red, the entire jaw is shown in it's grin, and the ears, eyelids, and nose appear to be missing. It can also be seen with other creepypasta characters, such as {{jeff_the_killer}}, who shares a similar grin with Smile Dog, especially it's distorted form. It's said the concept of this creepypasta was based on an image of {{satan}}.