Where is G quintuple sharp on the piano?

Just as G sharp is one semitone above G, and G double sharp is two semitones above G, G quintuple sharp can be found five chromatic semitones--equal in twelve-tone equal temperament to a perfect fourth--above G natural. G quintuple sharp is enharmonic to A triple sharp, B sharp, and--most notably--C, as well as D double flat, E quadruple flat and F quintuple flat.

On a piano, this note can be played by striking the white key immediately on the left of a pair of black keys.

Triple sharps, triple flats, quadruple sharps and the such are very rarely encountered, and so the inability to play a quintuple sharp on the piano will not severely disadvantage one. Wherever did you come across this one?