[WillKirkby]

Additionally, the GameBoy's bootrom compares the Nintendo logo from the cartridge with a copy stored in the bootrom, and refuses to boot if they don't match. However, several bootleg companies realised that the console reads the logo from the cartridge twice - once to display it and once to compare it. By abusing the precise timings involved, they could display a bootlegged logo while still passing the checks.

http://fuji.drillspirits.net/?post=87

[userbinator]

The half-logo edits are hilarious and show some playful creativity, one of the things that makes those bootleg/unlicensed games a very interesting scene.