This is a really strange one. White to move, mate in one. I doubt anybody will get this one (unless they've seen it before), so I'll put a hint in a spoiler.
The legend is that at the time this problem was created, the rules of promotion in chess did not stipulate that the promoted piece be of the same color as the pawn. This is the rule now, so the problem is not real according to the present day rules of chess.
This is a pretty tough one. White to move and mate it 3. It was made by Louis H. Jokisch. It is titled "Twins", although with the third variant it could be called "Triplets"
"This one was used by Kenneth S. Howard as a front piece for his collection of 200 Spectacular Chess Problems. It became a classic, as Howard said, "by pure chance," because it was the first problem, perhaps, to have a twin. B.G. Laws discovered that by shifting all pieces one square to the left, an entirely different problem with a different key was achieved. He published it as his own with "Apologies to Jokisch." It was then discovered that by moving the position two squares up and one to the right, a third and different problem results. It deserves inclusion here, not on its merit as a problem, but as a first of its kind."
"Jokisch lived in Illinois and was devoted to chess and music. A talent for the latter, and for mathematics, seem to be concomitant talents in a large percentage of chess masters."