The Canadian Destroyer is a flip piledriver-like maneuver. The name comes from Canadian and TNA wrestler Petey Williams, as he's the person most associated with the move. It's clearly a piledriver variant, but has usually been ruled as a legal maneuver in lucha libre matches.
The name only makes sense with Williams, but it's stuck as the generic idea for lack of a better idea. Ozz has dubbed this move 'La Darketa when using it as a finish. Teddy Hart used a double underhook version of this move while in AAA.