Expression used here and there by Adults
I haven’t a clue in the foggiest • It’s an abbreviation of the phrase “I haven’t (got) a clue in the foggiest”. When you really have no idea why something has happened or the answer to a question. Saying “not a foggy one” can be used depending on the individuals choice of changing the original phrase, but it is always understood by other Brits when used.
“Do you remember which bus stop we’re supposed to get off at?” “Not a foggy one, mate. I’m just following everyone else!”
Added November 2020 by anonymous
4 out of 8 English speakers have heard this