when a penis is so small that it looks like there is a crevice between your testicals that resembles a vagina, so hence balls and a vagina makes a ballgina
The act of stuffing your cock and one testicle between your legs, while leaving one testicle out. Therefore creating a vagina with one ball. hence, the one ballgina.
When a man has absolutely no idea about his pants size and wears pants that are way too small or tight. The act of hunting or searching for this is commonly referred to as a Ballgina Safari.
Person 1: Is that guy over there really wearing spandex?!?
Person 2: Yup, his ballgina is showing too. :-/