I also think White Queen / Emma Frost, because of her psychic powers, is a particularly good subject for this sort of thing. I think the feeling of physical intimacy from having your balls at the mercy of a woman is probably similar to the emotional intimacy you get from confessing your innermost thoughts and feelings. The sense of apprehension and expectation and fear and excitement that combines in both cases, like when you first tell a girl you love her, or when she threatens to kick your balls. Being so completely exposed and vulnerable and having put yourself completely at the mercy of another person, either emotionally or physically. I see a lot of similarities there between a woman knowing my innermost thoughts and feelings (and desires), and a woman having a grip on my balls. So a character that can exploit both of those most intimate vulnerabilities at the same time has a lot of potential.