There exists a GameCube Service Disk that was used by the Nintendo World Class Service to test and diagnose problems with the console and peripherals. It is assumed that once Nintendo retired the World Class Service, they took back the disks and destroyed them, which would explain why there are very few ever found.

This disk contains a fair amount of unused content, from unused sounds and unused test pictures to stereoscopic 3D test pictures.
Contributed by SonicManEXE