A corruption of Megurine Luka of the Vocaloid series by Sangatsu Youka. TakoLuka is a disembodied head with octopus tentacles for hair.
Origin: post #402301 (possibly by way of post #409008) - Detail: post #404807
Sometimes other characters are drawn in a similar fashion, thus Takoluka, much like the Yukkuri which may have inspired it, has become a meme as well.
This tag implicates megurine_luka (learn more).