When Two Flatworms Really Really Love Each Other...

I've recently discovered that penis fencing is not some unconventional sub-genre of man-on-man action porn. For some species, it is actually a perfectly conventional method of reproduction. Now that we've established that we're well within the limits of the Safe for Work zone, you can go back and press that link. Go ahead, don't you trust me? No sausages there, I promise.
Now that you know what I'm talking about, here's my take on the matter. In case you're a cowardly prude, and your web history means more to you than our friendship, prepare to be very, very confused.