And it's not a double sharp.

I saw it in [Miley Cyrus Fugue](https://www.youtube.com/watch?v=2mVuwOKA3UY?t=2m35s) in measure 88 between the 3rd and 4th beat for the right hand. It's being reached at 2:42-2:43 in the video and I don't hear anything special. Here is a screenshot for convenience:

[![Excerpt from Miley Cyrus Fugue, measures 84–91][1]][1]


  [1]: https://i.sstatic.net/lSFs5.png