I have no piercings, and nipple piercings do look ouchy ouchy to me. I saw one guy once with a ring dangling from each nipple while he was playing tennis on the adjacent court. I wondered if it was painful for him with those rings flopping around as he ran the court. He didn't seem to mind though.
I don't think it's a matter of ceeding contol of your body somehow to the opposite sex. Touching on what Xena wrote, I agree that the wearer is the one who is in control. When a women for example wears the stuff Xena described, I'd say she's very much in control.