Bats such as E. serotinus—which is common across Europe and Asia—are already known to have “unique and quite peculiar” reproductive behaviors, compared with other mammals, Fasel says. Males and females of many bat species can store sperm for months, and females can delay ovulation until after they hibernate, according to Orr. There are also some truly odd moments within the realm of kink, ranging anywhere from m/f couples looking for a unicorn (or another woman to hook up with the couple, without any strings attached): shortened form of "eight ball" - an eighth of an ounce of an illegal drug. Could I get a ball? I love balling a tighty pussy. In response, males seem to have adapted their genitals to push the membrane aside so that mating can take place, with the result being a larger than usual penis. What is known, however, suggests that bat reproduction can be quite unusual when compared to other species.

While collecting sperm samples from bats several years ago, University of Lausanne evolutionary biologist Nicolas Fasel observed dozens of bat erections and noticed that the species’ penis was “huge” and had an oddly shaped head. Once erect, the male serotine bat’s penis is almost a quarter of the length of the animal’s entire body—making it about seven times longer and wider than the female’s vagina.Professor Fasel suggested: "Bats use their tail membranes for flying and to capture the insects, and female bats also use them to cover their lower parts and protect themselves from males, but the males can then use these big penises to overcome the tail membrane and reach the vulva." But perhaps more importantly, their penises are too big for penetrative mating. Their erect members are more than seven times longer than the length of a female serotine bat’s vagina. The wide, heart-shaped heads, meanwhile, are also seven times wider than a female’s vaginal opening. “We were thinking it would be really difficult for [the penis] to enter anything,” study co-author Nicolas Fasel, a biologist at the University of Lausanne in Switzerland, says to Nature News’ Gayathri Vaidyanathan. But the recording may nonetheless prompt the rewriting of textbooks. Researchers believe the film of serotine bats is the first documented evidence of any mammal mating without intromission. In plain English, that’s having sex without penetration.

Most mammals mate with penetrative sex, but one peculiar bat species with an oversize, bulbous penis seems to sweep that assumption aside. New video evidence suggests that during copulation, the male serotine bat— Eptesicus serotinus—instead uses its penis like an arm to push away the female’s tail membrane and presses the tip against the vulva, according to research published in Current Biology. Over time, this can mean males and females of the same species evolve in response to each other as they try to get the upper hand. This is sexual conflict, and can involve changes in body size, characteristics and behaviour. Male serotine bats have long penises with bulbous heads. When erect, their penises measure roughly 0.6 inches (1.6 centimeters) long, which represents more than one-fifth of their 2.7-inch (7-centimeter) body length.

To the wrongly-rooted feelings of shame we sometimes harbor surrounding our kinky feelings and predilections: The females of some species, for example, are known to store sperm that allows them to mate before hibernation but only become pregnant after they’ve woken up. Other species fertilise their eggs immediately, but can then delay the development of the embryo until conditions are better to raise offspring.