A meme involving giant, disfigured heads resembling those of
Touhou characters. It originated on
2ch in early 2008 when an Anon tried to make a Shift_JIS portrait of
Reimu and Marisa and failed horribly. Another Anon thought the failed attempt was humorous and drew the infamous original picture (shown below right). Ever since
that fateful day, yukkuri heads have dominated parts of NicoNico and made cameos in numerous other pieces of Touhou fanart. Their catchphrase "Yukkuri shiteitte ne!" literally means "Do it slowly!", but has been more loosely translated as "Take it easy!" by the English-speaking Touhou community. This remains the basis for many of the jokes centered on yukkuris.
Reimu: This
stalking deformed head of me is quite annoying.
Yukkuri Reimu: Yukkuri shiteitte ne!