Olympian is an Achievement in Audiosurf. The requirements are to earn triple the score required for a Gold Medal on a song at least two minutes in length.
An easy way to get this achievement is just by playing any song on casual mode, considering the gold medal requirements are not difficult at all to obtain, and can most likely be achieved in the first minute of the song. If you feel as if that isn't an honest way to earn the achievement, you can play a longer song and hope that the red blocks rake up on the board. In this case, good luck.