That is a common internet prank using a image swap script. For example, someone looks for an image of a bunny on Google and posts it. They don’t know that the site they posted it from uses that script and replaces the “Goatse” (don’t Google that) image with the bunny.
Actually this was a troll that posted it. Usually early in the morning. Seems to me that I remember some changes in software and for awhile newbies couldn’t post threads.