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.