An inside joke related to Derpibooru.
Long story short: there is this one completely insane dude who apparently took it as his holy mission to spam the site with already uploaded pictures (duplicates, or dupes in short), and for the past few weeks, he kept reuploading this image
a couple times a day. He goes incredible
lengths to bypass any ban that can be applied to him, and according to the admins, he changes proxies twice a day and already had over 240 of them from the start of this year alone.
So yeah. Nightmare Dupe pops up on Derpibooru a few times a day, and nobody can stop it.
EDIT (28.05.2014): It seems that at this point this problem is gone for at least a few months now... but the image can still work as a reminder of this curious part of Derpibooru's history.
--------------- Inkscape SVG file: sta.sh/01hm1dj8w5am
(Linux compatible: sta.sh/0r9s82stn8k
) Textless version: sta.sh/2ymppa43s2z Original vector, no tracing involved.
--------------- Based on "My Little Pony: Friendship is Magic" by Lauren Faust.