“They had whatted the car?”

Question

The Cambridge Grammar of the English Language says this:

Echo what is syntactically very different from the interrogative pronoun what. It can replace words of more or less any category, and can take on the inflectional properties of that category — cf. You bought three whats? or even They had whatted the car?

CGEL does not use any symbols indicating questionable grammaticality or grammaticality in some dialects only for those examples; therefore, the authors consider the examples correct in all dialects of English, including International English. As the echo what would naturally occur in spoken English (as opposed to written English), it is difficult to ascertain whether the examples would sound idiomatic in major English dialects (e.g. British English, American English) using Google Search. So, my question is:

Which of these are more natural in various spoken English dialects?

They had what the car?

They had whatted the car?

You bought three what?

You bought three whats?

EDIT: Or more generally, what constitutes idiomatic use of echo what in British and American English?

Answer 1

If you're going to use what as a verb in this way, you have to decline it as usual. So this is correct:

They had whatted the car?

However, while the above is certainly comprehensible and usable in speech, I would probably just say They did what to the car?

When using what as a pronoun, I prefer keeping it indeclinable:

They bought three what?

However, the plural version is also acceptable:

They bought three whats?

There's no difference of meaning between these. Some speakers may prefer one form, and some the other, but there are no firm rules or conventions about pluralization of what.

Answer 2

It depends on which word you are replacing with what, you should usually treat what in the same way as the word that it replaces.

So, if you replace clean in They cleaned the car it would be They watted the car?, but if you replace drive in They drove the car it doesn't have a suffix so it would be They what the car?.

The idea is that the "whated" sentence should be as close to the original to be recognisable even with multiple replacements, like for example They cleaned the car into Who whatted the what?.

Answer 3

I'm not an expert, but I had the same reaction as JSBangs. I would say "They did what to (or other preposition) the car?" or maybe less frequently "They had whatted the car?"

For the record, I'm from the US Northeast.

Answer 4

Both sound natural to me — at least from my ear that normally hears American English when I'm home and British English when I'm abroad. It depends though on the group that's using it — some would use this more than others. If it's been an established within a group — I think it comes off as more natural.