Quote from Frasier in Dinner at Eight-ish
Frasier: Doctors Sternin and Crane are proud to announce that they are now officially POSSLQ's. [chuckles] Lilith: It means "Persons of the Opposite Sex Sharing Living Quarters." Frasier: Yes. Diane: Oh. Frasier: You see, it's a little, uh, lovers' in-joke we picked up from a Census Bureau acronym. Woody: Oh, I love those.