Who the HELL would actually think a guy named "YoMama" is a girl? I've met so many people using that name over these past several years and not a single one of them was female. I knew you were a guy, don't worry. Never even played with you in-game.
...however, I don't know if it's appropriate for players to assume females like to be called things like that in the first place. Female or not a simple "Hello" or "What's up" would work.