I'm 17, I work at McDonald's and have worked there for over a year. many girls here have a lot of piercings in their ears. My manager has 4 in each ear, most girls have at least 2 in each ear. Saturday night I got my ears pierced, 1 black diamond stud in each ear. Will post pictures if needed. It's nothing flashy or showy. My manager asked me to take them out, when I asked why, she said guys weren't allowed to wear earrings. I work the same exact job as all of the girls, and I'm not allowed to wear 1 earring in each ear but they are. All of my managers (7 of them) are girls if it matters. What can I do or say?

EDIT: I live in Pennsylvania