Example 1: A fictional character with unreasonable amounts of power, ability, or skill. As stated by the name, they are usually unexplained, yet on the off-chance may be. If they are explained, the explanation is lacking or downright retarded.
Example 2: A sudden burst in might, whether literal, political, or otherwise.
Derived from a Metal Gear Solid flash that joked about Volgin at times, poking fun at his control over lightning.
Well here comes Mr. Gary Sue and his fuckin' unexplained lightning powers. Say bye to your characters, guys.
Those were some unexplained lightning powers Hitler whipped out of his ass.