A household is a business given over to caring for small, temporarily insane people.

-- Clark Glymour, What Went Wrong: Reflections on Science by Observation

Longer version:

A household is a business given over to caring for small, temporarily insane people, a business subject to cash-flow problems, endless legal harassments, run by people who expect to have sex with each other, who occupy the same space, and who go nuts when either party has sex with anyone else. Once in marriage, a lot of people try to get out as fast as religious tradition, poverty, or devotion to children permits.

(I really like the short one for "small, temporarily insane people", but the one above will tickle many a LW reader's funny bone.)

Via CRS.