According to the Question Close Stats in the 10k Tools here on Meta Stack Exchange, Shog9 created a new close reason in June 2013 that stated:
Questions about unicorns are off-topic because I really hate unicorns. For more information, bite my shiny metal horn.
The close reason was apparently removed the same day.
I know that unicorns have been a meme on Stack Exchange for quite a while, but I haven't been able to figure out exactly how that led to this very short-lived close reason.
What actually happened on the site on June 19, 2013 that triggered the creation and prompt removal of this close reason?