R'lyeh's architecture does not follow Euclidian Geometry, but it is unknown whether it is hyperbolic or ellipsoid.
1 - The home of Cthulhu in H. P. Lovecraft's "Cthulhu Mythos." See Wikipedia for in-depth information quickly, or read the book(s).
2 - A way of refering to one's hometown as being a complete nowhere or shithole.
3 - A very frightening place.
(In his house at R'lyeh dead Cthulhu waits dreaming)
"Where do you live?"
"Fuck, man... R'lyeh..."
"I just spent the weekend at my great-aunt's in R'lhey... *shudders*"