When a person loses a significant amount of weight and develops loose skin on the belly, it looks like vaginal lips when they bend over and the skin hangs down. Typically, the vaginal lips are centered around the belly button.
"I'm dating this guy who used to be really fat, which, as a bisexual is nice... because he has both a penis and bellgina."
when a girl, Usually one whom has sex alot, has a vagina which is so wide that it meets her belly button, thus giving birth to the bellgina
Man, that girl has been whacked so many times that she has a bellgina!