When a girl acts as though she is God's gift to mankind, simply because she plays games.
When she realizes that nerds and geeks will flock to her and shower her with attention for being a rarity - she does everything she can to ensure she continues to get said attention.
Buying geeky accessories, joining groups like the D20 Girls, posting suggestive + geeky pictures to the Internet, fawning over Magic cards, incessantly talking about D&D, and basically wrapping herself and her identity up completely in being a nerdy/geeky/gamer - solely because it gets her the attention she couldn't get from ANYONE ELSE.
Also known, in other subcultures, as a faker, wannabe, or poser.
John: Dude, did you see the skanky picture Tracy posted of her d20 tramp stamp?
Smith: Yeah, I saw her. I bet she doesn't even know what THAC0 is. She's got a bad case of Gamer Girl Syndrome.