Suggested by Berky93 - 12 May 2007
If you take a Game Boy advanced (it will probably work with color too, but I haven't tried it yet) and insert a Gameboy game that was for the original, non-color Gameboy, (I used super Mario land 2) you can change the entire game to be tinted a certain color.
All you need to do is when you are at the screen that says Nintendo, press one of the four d-pad buttons, or all of them. Each one has a different color.
Yeah it says how to do it in the consoles manual for the GBC and the GBA Mo - Jun 21 2009 5:01PM
This worked on any game from the original gameboy that was designed to work with Super Gameboy. Matt - Mar 24 2008 4:48AM
Not an Easter egg, ney. But then it is in the 'non eggs' section! Bongo - Aug 23 2007 3:10AM
You could do this on the Gameboy color with the Pokemon games. Old news <.< Zen - May 13 2007 3:27PM
It seems that this is mentioned in the user manual of gameboy colour.. ke - May 13 2007 11:58AM