The image.
On March 12, 2007 one the /b/ board of 4chan, an anonymous user posted a .GIF image. At a first glance, strangely, the .GIF image wasn't animated. It was titled IM_HAPPY.GIF, and showed what appeared to be a drawing of a smiley face, only with realistic looking eyes and mouth. People who clicked on it saw the smiley face's smile slowly turn into a frown, and the eyes taking on an angrier appearance.
The smiley face would then scream loudly - loud enough to burst eardrums - and gruesome images of animals being tortured, rapes, bomb test victims, aborted fetuses, and mutilated bodies would flash by quickly. After about five minutes, it would show the text Have nice day (sic), and the user's computer would automatically close out of the browser and would stop working, as if a virus had corrupted the hard drive.
People whose computers were infected would shortly be found in their homes, skinned and mutilated, with a smiley face painted in blood on the floor next to their corpses. moot, the founder of 4chan, would always claim that the picture never existed, and that the murders were unrelated. However, somewhere in the archives, the picture still exists. Most people who attempt to post it are usually swiftly banned by moot.
Originally written by Multiverseman