When talking about missed evolutionary chances, you'll always end up at the cloaca. One hole for all your waste? Holy shit, who wouldn't want that? In this cutthroat 24-hour economy in which every second counts, such a multifunctional body cavity just might give you the edge on your multi-hole competitors. Imagine the time you would save shitting and pissing simultaneously. Just one hole to clean. Just one place to scratch. Just one cavity for doctors to examine. Imagine what it would mean for our country's medical costs!
And it can also be used for fucking. Man, you couldn't have thought of it even if you wanted to. It's the strongest argument for intelligent design we have right now. Unfortunately, this "designer" decided to give His best creation to a bunch of idiotic animals that don't know how good they've got it. Fucking dumbass beasts like fish, newts, and thrushes. They aren't worthy to wear the cloaca if you ask me. They can't handle it, can't see the added value--and because of that do not exploit it to its fullest. Singing birds have yet to deal with medical costs. Pearls to the pigs.
And what, I ask you, have these flying, crawling, and swimming animals done for the cloaca's image? Not much good I can tell you! Would you like to have the reproductive organ of a teleost fish? Hell no. But if a creature along the lines of a Sasha Grey, or anyone whose sexual habits are closely observed by the masses, were to sport a cloaca, I believe we would have an uprising of Egyptian proportions. Multi-holed people everywhere would demand the medical advances required to change their plumbing to the efficient and, dare I say it, sexy, cloaca. I for one, would be the first in line.
The cloaca. Such a pity.