Refers to a person, usually female, who will engage in sexual acts other than vaginal penetration of a penis. Vaginal penetration of a penis is "sex" and therefore evil--so to maintain "virginity", Roman Catholic Virgins will engage in manual, oral, anal, or anything else that isn't vaginal. Personally, I think it's a sign of serious hypocrisy.
"Bless me Father, for I have sinned. It's been one week since my last confession."
"Have you committed sins of the flesh?"
"No, I'm still a virgin."
***This penitent is lying: Manual, Oral, and Anal Sex are all SEX. It's right there in the titles!***
"I went out with this chick from St. Thomas Aquinas last night."
"Hell yeah--she's Catholic so she took it up the ass! I fucking love Catholic virgins!"