GBS
GBS may mean Guillain-Barre syndrome.
GBS is also short for Gameboy Sound System. It is akin to the sound system of the Nintendo Entertainment System (NES), the difference being that GBS has a higher pitch than NES sound format.
The GBS has two square waves, a voluntary channel (like a triangle/DPCM combo) and a noise channel; however, the triangle/DPCM channels are not separated as in the NES. Gameboy music sounds very similar to that of the NES, although its pitch is higher. There are various players with which to play GBS files.
GBS is the post-nominal letters for the Gold Bauhinia Star, the second highest rank in the Hong Kong honours system.
GBS stands for General Bullshit, and is one of the main boards at the Something Awful forums.