Cleaning lady: "Sorry I had no idea you wasn't effable, I'll come back later"
that is to say since effable as a slang term for some someone that one might like to have sex with exists, it is a reasonable pun to make with ineffable as being, well, not effable. However one should probably be able to realize the ineffable in question is not a pun on the slang term and figure things out. Somewhat embarrassing really.
on edit: added in disturb, must have missed it because very tired.
I read it last year. I found it to be quit boring and it also felt kinda "dated" in the sense that more recent SF is more space-y. However, the social constructs were well thought out.
If the second, there was a lot of sci-fi set in space for decades before The Left Hand of Darkness, and the cultural focus of that book and a lot of the new wave of science fiction writers of that time was a reaction against the outdated space focused science fiction of the previous generations.