Poor Levi gets called a girl all the time. He has longer hair, but everything I ever put on him is BOY. Blue harness and collar and leash...manly clothes or jacket if he's wearing it. I think it's the hair that throws people off for him.
I've gotten used to it, but it drives my brother nuts. My brother babysits Levi most days while I'm at work, and it's become his little soapbox. He's always like, "I don't know why people think all long-haired breeds are girls! Where do they think they are coming from if every Yorkie is a girl?"