Green’s Dictionary of Slang

fluffy-duck v.

[rhy. sl. = fuck v. (1)]

(Aus.) to have sexual intercourse.

[Aus]R. Aven-Bray Ridgey-Didge Oz Jack Lang 14: She flung aside her starboard brace and bit and gently scratched her prat / And with a split arsed grin she answered him, / You can go and fluffy duck your ballarat.