The Falkland Islands' own Sasha Arkhipkin (whom I missed meeting on his last trip to California--sorrow!) has discovered that males of a particular deep-sea squid species have penises as long as their bodies. And they can stretch even longer.

It's a wild story, but for those unaccustomed to staring at squid innards, the photos may not be particularly striking. Therefore, I provide this helpful contrast: the reproductive organs of a male Humboldt squid. (Note that the penis is hiding slyly underneath one of the gills--but still, it's nowhere near Onykia-sized.)

Male Humboldts do have a specially modified arm that they presumably use to hand over those needle-like spermatophores to the female. I say presumably, because mating in this species--like so many others--has never been witnessed.