Here's a question that's a little off the usual format, but problem questions like this have been done before and are on topic, so here we go!
Question: Can you find the mysterious mate in one? The trick is not board rotation, removing a piece, retracting any moves, completing a move, or an illegal move-there is but one solution. Have fun solving!
[Title "White checkmates Black in one move"] [FEN "5nRQ/6PR/1p6/p2P4/p1B5/3Pp3/8/1b1K4 w - - 0 1"]