To fuck in a way that is playful and shameless. One who "fiducks" could be shootin' the shit with others or simply humping someone's brains out. Fiduck is also typically used by psuedo Canadians to express disbelief, confusion, or malcontent as seen in the first example.
1. "Fiduckin' eh!"
2. "You are a fiducking tool!"
3. "I got fiducked last night"
4. "You are one messed up mother fiducker"
yeah... you can pretty much make up anything you fiduckin like...