Be careful when you ask a modern British woman ‘how her father is’. You know not what you’re asking! She might even slap you.
The origin of the phrase is open to interpretation. The Urban Dictionary has seven thoughts about where it could have come from.
The first instance about the phrase “How is your father?” is hilarious.
Writer and historian Michael Kelly, a New Zealander, traces the origin of the expression “How’s your father?” to the Victorian era.
In those days, men with daughters were very protective. The fathers took extraordinary measures to safeguard the virtue of their unmarried daughters.
Unmarried girls were kept within the bosom of their family and chaperoned on excursions. On those occasions when let out-of-bounds for social events, their fathers would often go with them discreetly.
Believe it or not, those fathers used to hide underneath the voluminous skirts of their daughters, ready to pounce on any man who transgressed the bounds of propriety.
This was okay for a father with a single daughter. But how about a father with more than one daughter? He couldn’t be everywhere at once! So, a suitor having a discrete vis-à-vis with his girl, to find out her father’s whereabouts would cautiously ask: “Annie, how is your father?“
If the girl’s father was now under her skirts, she would glance downwards to mean ‘Not now, Peter!’. She would then reply, “My father is well, thank you.” She might even add “He is alert and vigorous as ever, and maintains his interest in rusty castrating implements.“
Her beau would then say, “I have always had the greatest respect for your father, and of course for you. Let us hold hands and think about the Queen for a while.“
If the girl’s father was elsewhere, she might reply, “The mad old bastard is now between my sister Elizabeth’s thighs. Let us go into the garden and rut like stoats.“
Hence, the phrase “How is your father?” became a euphemism for you-know-what.