fiddle with

verb4

1. •
   To manipulate or toy with (an object), especially in a nervous, restless or aimless manner.

   • Stop fiddling with your food!
2. •
   To tinker with: to make small adjustments or improvements to (something), especially in an experimental or unskilled manner.

   • If you fiddle with the controls, you might be able to get a better TV picture.
   • The deadline for my report is two o'clock, but I'm still fiddling with it.
3. •
   (figurative) To manipulate in order to gain something for oneself.

   • Don't Fiddle With Sellers Who Have No Equity — 2004
4. •
   [with oneself] (informal, euphemistic) To masturbate.