Green’s Dictionary of Slang

fiddly-fuck n.

[var. on fiddler’s fuck under fiddler n.3 ]

(US) anything considered utterly insignificant.

[US] oral testimony in Lighter HDAS I.
[US]S. King Dreamcatcher 355: They play fiddly-fuck for half a century before getting this far.
www.dailyreckless.co.uk 🌐 This occurs when the computer salesman explains sixteen bit digital processing to you and expects you to understand what the fiddly fuck he is on about.
posting at www.thedugout.tv 2 May 🌐 I love that I can do anything I choose to without giving a fiddly fuck what anyone (like the above type of person) thinks about it.

In phrases