Ask a hard question, get a short answer. Damfino is damned if I know, said so fast it becomes a single word.

J. Redding Ware put it in Passing English of the Victorian Era (1909) with a label — Anglo-American — and an admiring description: the last instance of abbreviation and obscure swearing. The swearing is obscure because it is hidden. Damned is right there at the front, but run together with if I know it slips past as a noise rather than an oath.

Ware's example is a college joke. A student is asked what he intends to do after graduating. Damfino, he says; preach, I s'pose.

That joke is older than Ware's book, and American. Green's Dictionary of Slang finds it in 1871 in the Eaton Weekly Democrat: a gentleman asks a Williams College student what he will do after he graduates, and gets damfino for an answer. Green marks the word as originally US.

It did not stay there. By 1886 London's Sporting Times was using it — Where's your hat, dear? Damfino! — and Green has it in a Sydney paper in 1895 too. That spread is why Ware, writing about the English of Victoria's reign, gave it a place and called it Anglo-American.

It is still a useful word. Most ways of saying I don't know sound either sheepish or rude. Damfino manages to be both and neither: frank, a little cross, and too silly to take offence at.