A popular image macro featuring various owls with the phrase "O RLY?" captioned underneath used primarily as a sarcastic rejoinder. Other owl images with the phrases "YA RLY!" and "NO WAI!" generally appear as well. Use of the image is seen by many as trolling, and the term Owl Bombing was coined to describe the repeated use of the owl pictures in a thread.
The first documented appearance of the image on the Octopus Overlords forum seems to be in this thread from November 2005 where Msduncan requests a copy of the image. The use of the image sparked controversy in late January 2006 when used repeatedly in various threads (ex. 1, ex. 2) started by U2K Tha Greate$t, ultimately leading to several heated exchanges with moderators in the Meta Forum. These threads were later nicknamed Hooterloo, an homage of sorts to the earlier forum drama The Battle of Fucktard Ridge.
Recent use of O RLY? images still occur but with lesser frequency and with little to no drama involved.