Wiktionary
i hadn't the foggiest
vb. (en-past of: I haven't the foggiest)
Usage examples of "i hadn't the foggiest".
But I hadn't the foggiest idea of how to go about purifying the stuff.
Beldaran knew where she was going, but I hadn't the foggiest notion of my destination.
I wanted everyone to think I hadn't the foggiest notion of heading for Sun-side.