Number 2. Like many other marsupials, the penises of male koalas have two prongs. But, that’s nothing compared to the female, which has two vaginas and what’s called a vaginal cul-de-sac. Sperm travels up the vaginas on either side, and babies leave through the cul-de-sac, actually breaking through the bottom. After birth, the cul-de-sac heals.