Let's break down why this is the case:
* Fiddly: This word describes something that is intricate, difficult, or requiring a lot of precision.
* Foo: This word is a placeholder or a nonsensical word often used in technical contexts or as a joke.
Therefore, "fiddly foo" could potentially be used to describe something that is:
* Difficult to work with: A fiddly foo could be a complicated piece of machinery or a intricate design.
* A nonsensical or hypothetical object: It could be used in a humorous or satirical context to refer to something that doesn't actually exist.
However, without any specific context or usage, "fiddly foo" doesn't hold a clear meaning and is unlikely to be a widely recognized phrase.