A corruption of Megurine Luka of the Vocaloid series, originally created by sanpati in post #402301 (possibly by way of post #409008). TakoLuka (たこルカ, literally "octopus Luka") is a disembodied head with octopus tentacles for hair.
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).