From the game F-Zero GX for the Nintendo Gamecube
In F-Zero GX's 3rd cup, on the last level (Big Blue Ordeal), there is a strategy to go off the first jump, and then fly around the level, to get insanely fast times. This takes practice, but go quickly enough so that you get a score under 20 seconds (this worked with 16). Rather than saving your score, the game will accidentally think you are in Grand Prix mode and it won't record your score.
Submitted by: Jesse