Of course you can...NOT. It's like wanting to play PS3 games on a Wii. PSP and Gameboys are both from different companies, there is no way to play GB games into a PSP.
Gaming is not a sport, well not for the body at least. Gaming is more for entertainment and for the mind. However if you spend your whole life playing video games youll end up a fat, unhealthy person that has trouble with even walking. Plus you might get addicted with the game
Does your friend entered his E-Mail or a free web mail like MSN? My two friends had the same problem because they entered their MSN instead of E-Mail adress.