Slugs - the invertebrate kind, not the leaden ones, or the bipedal ones.
I was visiting some friends in the almost-countryside over the weekend, and late at night, when it gets cool and dark, their lawn and deck get overrun by mobile dog turds.
I mean, Ewwwww. Other than being totally gross, and leaving that indestructible slime all over everything, what is the point of slugs??
AND, I had the misfortune to see two of them having sex. At least I think it was sex. I don't know. The science nerd part of my brain was totally fascinated, but the rest of my brain was completely grossed out.