מיט װאָס מען עסט עס

In Yiddish, if you wish to say "I am utterly bewildered, I do not have even the shred of the beginning of a clue," you can say:

“ איך װײס נישט מיט װאָס מען עסט עס(Ikh veys nisht mit vos men est es)” which literally means “I don’t know how to eat it” or “I don’t know with what you eat it” The possible ambiguity of this expression is one of the subjects of this comic piece.

The consequences of cluelessness with regard to one’s eating implements are discussed by Hotchkiss and the General in Getting Married by GBS. Hotchkiss has just explained that when in the service, he sabotaged the plans of his commanding officer because he would take orders only from a gentleman (spellings and punctuations as in the original):

THE GENERAL. And pray, sir, on what ground do you dare allege that Major Billiter is not a gentleman?

HOTCHKISS. By an infallible sign: one of those trifles that stamp a man. He eats rice pudding with a spoon.

THE GENERAL. [very angry] Confound you, I eat rice pudding with a spoon. Now!

HOTCHKISS. Oh, so do I, frequently. But there are ways of doing these things. Billiter’s way was unmistakeable.

I was very young and utterly bewildered the first time I read this, and to this day it seems to me that anything other than a spoon is heavy equipment, pudding-wise, but numerous sites corroborate the fork-for-pudding position.