i witnessed the mating of two great grey slugs.
perhaps that doesn't count as strange, as it probably happens all the time (to judge from the enormous slug population, that is), but it was definitely new to me.
lots of slime.
their penises (slugs are hermaphrodites, by the way) were about half the length of their bodies.
it was very very very slow.
very slow.
sluggish, one might say.
but gosh, they were having a good time. didn't mind me watching at all.