Perhaps it's only funny if you're familiar with Lovecraft's work, so let me explain the joke a bit.
Cthulhu is imprisoned on earth, dead but dreaming, etc. The proper incantation can bring Him back, and part of that incantation is what the analyst reads. Obviously, he read the dangerous parts of it, and summed Cthulhu.
And by the way, it's not from France, it's on a French Web site. The site it's originally from is actually Japanese. If you're going to make racist jokes, at least make them right.