My reaction to scoff - that's not a fencing penis, THIS is a fencing penis.
Those of you who have seen Dr Tatiana's Sex Advice for All Creation (the book it's based on is excellent) might have seen the penis-fencing flatworms - Oyster Leeches, in this case - that were duking it out in an effort to get the other one pregnant.
The video, not from Tatiana's sadly, is of such a duel - it's amazingly fast and brutal for such a slow and delicate creature, with each flatworm stabbing away viciously with its penises, and twisting to avoid being stabbed back.
I HAVE TEH DUMB, I CAN NOT BRAIN
everybody is of course quite right, this was posted just a few months ago and despite reading the timetag at least three times, I completely failed to realise that it was the first 4 numerals, not the last two, that indicated the year. Ah well, I guess I'll just have to put it down to the 50 or so time-codes I have to note down each day, all in a 24hr:day:month:year format