Reactions come hard and fast following stimulating segment by Japanese public broadcaster.

Japan is not a country that’s particularly shy about fetishes and sexual desires, and with the veil of anonymity that online interactions provide, there are even fewer inhibitions when it comes to discussing such matters on social media. But even with all that said, many Japanese Twitter users were still shocked when the platform was suddenly and overwhelmingly taken over by “penis fencing.”

The term started trending on Thursday night, and its stimulating nature produced a wad of comments such as:

“Why is ‘penis fencing’ showing up in my recommended tweets?”
“I’ve been sitting here laughing at ‘penis fencing’ trending for 10 minutes straight.”
“I’m at work now, but I can’t get penis fencing out of my head.”
“I feel like all I’ve been talking about for the past 12 hours is penis fencing.”

Your first instinct may be to assume that penis fencing is a genre of historical-era boys’ love manga or some other dynamic kink from a subset of the otaku/fujoshi community, one that’s just now leaking out into the mainstream, perhaps as a result of the long draught of Comiket doujinshi events not giving such-oriented enthusiasts an outlet for their passion. The truth, though, is that penis fencing isn’t an anime/manga thing at all, but a science/marine biology one.

On Thursday evening, Japanese public broadcaster NHK aired the latest installment of its annual documentary series Hentoko Dobutsu Academy, or Unusual Animal Academy. For one segment the in-studio panel turned their attention to flatworms and learned that certain species’ mating habits include a practice called penis fencing.

▼ At this point, you might have finally stopped giggling at the term “penis fencing.” Please feel free to now commence giggling at the fact that one species of flatworm that penis fences is named Pseudobiceros hancockanus.

The name might have you imagining that male flatworms compete for mates by battering their dongs into each other, with whoever’s member survives the ordeal in working order going on to mate with the female. The truth, though, is even more shocking. Penis fencing flatworms are hermaphroditic, having both male and female reproductive organs. When they penis fence, they’re each trying to impregnate the other, while avoiding getting impregnated themselves. The duel ends with the victor injecting its sperm into the loser’s body – yes, injecting. Apparently any opening they can find or create with their penis will do, and as long as the sperm gets inside the loser’s body it can find its own way to the loser’s ovaries.

▼ Incidentally, both the Pseudobiceros hancockanus and Pseudobiceros bedfordi, pictured below, are equipped with two penises, making them the Miyamoto Musashis of dick fighting.

Of course, no matter how deep your respect for science and the majesty of nature are, it’s impossible to not see humor in the term “penis fencing” (which in Japanese is pronounced penisu fenshingu) being bandied about by Japan’s most respected television station, and Japanese Twitter users continued pleasuring themselves with jokes long after the broadcast ended.

“Flatworms are so BL.”
“I get the feeling that now that the term is out there, we’re going to see some unique things online.”
“’Penis fencing’ is definitely going to become a hentai manga term after this.”
“I would totally watch penis fencing as an Olympic event.”
“I was watching the program with my son, and asked me ‘So Dad, did you stab Mom with something?’ All I could do was say “Yes, that’s right.”

Scientists aren’t exactly sure why penis fencing is how flatworms get it on. One theory is that since bearing the fertilized eggs is a physical burden, it’s something they want to avoid, while others think it might be a natural selection-style way to help the species thrive by allowing the duel’s winner to potentially impregnate other mates during the gestation period. Either way, though, the next time you’re feeling frustrated with human dating dilemmas just remember that things could be a lot more complicated if you were a flatworm.

Sources: Twitter via Hachima Kiko, Wikipedia (1, 2)
Top image: Pakutaso (edited by SoraNews24)
Insert images: Wikipedia (1, 2)
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