In pretty much every Super Mario platformer game after Super Mario Bros 3, there is a "P-switch" which turns blocks into coins and vice-versa (and sometimes some other thing, like make special blocks appear). Many people assume it stands for "Power" and some think it might stand for "Paratroopa" because "P-wings" let you fly like a Paratroopa (sort of), but these are all unsourced guesses.
Incredibly, as far as I can tell, the internet simply does not know what the P actually stand for!
