Cthulhu is a fictional cosmic entity created by writer H. P. Lovecraft and first introduced in the short story "The Call of Cthulhu", published in the American pulp magazine Weird Tales in 1928.
In this episode it is discovered how Kenny continues to show up despite the fact that he dies constantly.
The scene in which Cartman tried to cutely seduce Cthulhu is an indirect reference to the iconic scene in "My Neighbor Totoro" in which Mei meets Totoro in his cave.
Kenny in his Mysterion costume, with a blue cape casting a shadow over his head, bears a resemblance to the DC character and Teen Titan Raven, the half-demon child of Trigon and Arella.