As TV Tropes quoted:
"The Hero is on the ropes, getting his butt kicked by the villain. In desperation, the hero pulls out a weapon and hurls it.
He misses! Or maybe the villain dodges. Either way, the bad guy smirks or laughs at this futile final act of defiance as he closes for the kill...
... only to have the thrown weapon come back and hit him from behind, knocking him out or even killing him. Turns out, the weapon was in fact a Precision-Guided Boomerang (sometimes obviously so), or had boomerang-like properties"

Riolu VS. Girafarig, and it so happens to be involving a hammer that seems to have it out for that Girafarig, Riolu swings, and misses! And then the hammer slams to the head of the Girafarig causing him to plummet down to the ground, defeated. Riolu wins!