Squick: One of Fafhrd's more useful girlfriends is Kreeshka. She's a Ghoul who he captured in battle. Ghouls in Nehwon are basically nudist humans with normal bones but transparent skin, organs, et cetera, so except for some cool lighting effects they look exactly like animated skeletons (And yes, Fafhrd does ask "how do you see?". He even gets an answer.) Some people seem to be disturbed by thinking of the visual aspects of their sexual relationship. For some reason the description of seeing her chew, swallow, and digest a piece of raw meat that remains visible the entire time doesn't seem to faze anyone. Also mentioned is that female Ghouls at least, wear make-up so you can see the parts you can't see normally.
"Weird Al" Effect: On both ends — it itself was intended to mock earlier conventions of a more staid fantasy genre; as the genre became more and more free-wheeling and the Conan-style fantasy novels it was lampooning faded from view, it ended up getting many humorous references from elsewhere itself. In particular, Ankh-Morpork of Discworld started as a Lankhmar parody before arguably becoming more well-known.