You’d think we would have come to the end of the animal penis facts by now, right? Wrong! Banana slugs can grow to be between 6 and 8 inches long. And their penises can also be 6 to 8 inches long. And those penises emerge from their heads. We’re pretty sure banana slugs — which, as a reminder, already kind of look like penises — are evidence of nature playing a joke on itself.
The mating ritual of the flatworm is legit insane. The animals are hermaphroditic (meaning they have both ovaries and testes). In order to procreate, they use their penises to stab each other in a move very creatively named “Penis Fencing.” Finally, one of the flatworms stabs the other close enough to the ovaries to inseminate the other. True love!