From my notebook, which is full of exquisite handwriting, I have just misread the word fingernails as fingernauts (see picture below; word circled).
The full phrase was, I'm at war with my fingernauts (sic). I’m not sure what the fingernauts were doing for me to declare war on them, but as I rarely declare war without a very good reason (your hair is the wrong shape, you're not as tall as I thought you were, it's raining, etc.) then they must have been doing something pretty shocking.
Of course, we are all at war with our fingernails, aren’t we?