Lesbian joke

A woman goes to the doctor's office. "Doctor, I've got a strange problem I need your opinion on." "Could you describe the symptoms to me ?" he asked. "Well, it's easier if I show you," she said and, standing up, proceeded to undress. When she was down to her underwear she sat on the edge of the examining table and spread her legs to reveal two small green circles on her inner thighs. "They don't hurt or anything, but I was a little worried about them." The doctor looked closely at the two circles and said, "Are you a lesbian, by any chance ?" Embarrassed and slightly uneasy with this question coming from a man with his head between her thighs, she replied "Well, yes, I am actually. Why do you ask?" "Well, I'm afraid you'll have to tell your girlfriend that her earrings are not real gold."