Has anyone noticed the recent fashion for this expression? The full version is ‘Who would have thunk it?’, where thunk is used as a pseudo-archaic past participle of think (by analogy with drink/drunk). This rhetorical question (similar to ‘Would you believe it?’) can be used to express genuine surprise:
Two games and nul points for Inter after their home defeat to Bayern Munich. Who’d have thunk it?
But, just as often, it is heavily ironic:
Dr Una Coales BA (Hons), MD, FRCS, MRCGP told us that ten years of binge drink is not good for you! Who would have thunk it?
The more standard version (‘Who would have thought it?’) is used in similar ways:
The Magazine now is in its 13th year – who would have thought it! (genuine surprise, not irony)
I heard one of the classics on the BBC the other day: “Two paintings have been stolen by thieves”. Who’d have thought it – thieves stealing something? (irony)
What is noticeable, though, is that version with thunk appears only rarely in its fully spelled-out form. Of the 60 odd hits in our corpus, only a handful appear as ‘Who would have (or who’d have) thunk it?’. Much more common are cases like this:
A sort of socialism among the Monte Carlo class. Who’d a thunk it?
Even the original line-up of Dinosaur Jr will be back on stage together this summer – who’d of thunk it?
He finds that he can have plenty of fun just being friends with a girl (who da thunk?) without being intimate.
It seems that, once someone opts for the form thunk instead of thought, they are already committed to a ‘nonstandard’ usage – so why not go the whole hog?
Where did it come from? One theory is that it was used by the ventriloquist Edgar Bergen – who had radio shows in the 1940s and 1950s – as the catchphrase of his not very bright dummy Mortimer Snerd. But whether Bergen actually invented the expression isn’t clear.
At any rate, the verb is showing signs of escaping from its fixed phrase, and being used as a straight alternative to thought:
Q: Your thoughts on playing the sold-out Roxy in Atlanta in a few weeks? A: Never woulda thunk it.
Didn’t sleep well, feeling a bit sick after learning that what I’d thunk was a rabbit that we barbecued was actually a corgi.
The ground was being prepared. We would have open reviews where the unthinkable would be thunk.
And in a final (?) development, Google has quite a few instances of the same form being used with the rare verb unthink (to put a thought out of your mind):
Thanks for a thought that can’t be unthunk.
Who ever would have thunk it could be so versatile?