Scarbo is a song in Piano Tiles 2 Umod, written by Maurice Ravel, with very high speeds and series of double tiles along with single and holding tiles. It is labeled as "IMPOSSIBLE" in the game. The reason I think is labeled as impossible is because of many series of slightly long double tiles.
It is possible with great skill to pass one lap of this level, however, as the speed increases with each lap completed the song becomes impossible for even the best most talented players.
The speed for Scarbo: 10.3 / 10.367 / 10.433