The ridiculosity starts at birth.
Genesis says it's the curse of Eve: "Unto the woman he said, I will greatly multiply thy sorrow and thy conception; in sorrow thou shalt bring forth children..." (Gen 3:16a)
This is one of those places where, speaking metaphorically of course, the Bible nails it. That curse came about because Eve ate of the fruit of the Tree of Knowledge of Good and Evil. If you're willing to look mythically rather than literally at that whole passage, it's almost as if the knowledge, or consciousness, brings about the curse. (The instant they eat that fruit they are suddenly self-conscious...)
Human beings have more labour pains than any animal I can think of. And why? Largely because our brain pans are grossly outsized relative to our bodies. While brain size alone is an almost meaningless measure of intelligence, brain size relative to body size is much more significant. I've no doubt that if you wander back into the mists of prehistory, you'll find homo erectus giving birth with about the same drama as you or I would have taking a dump. (Wait a second, there's two things wrong with that sentence: one, my dumps are pretty damn dramatic, and two...take a dump? Who does that? I leave mine, myself.)
In any event, since giving birth is pretty much a biological imperative, you would think that birth canals would be better suited to the task. I say this meaning no disrespect to mothers whatsoever; on the contrary, I stand in awe of the pain they willingly endure. But why should they have to?
Pain in general baffles me. Physical pain is stupid. I get that it's a critical alarm to let you know something is wrong. You wouldn't want Riley-Day syndrome, much as the inability to feel pain sounds attractive. Your lifespan is drastically reduced, for obvious reasons.
But that said, pain should have some kind of dimmer switch. There are still any number of pains that announce themselves, and announce themselves, and announce themselves, and there's not a goddamn thing in the world you can do about them. Ask anyone suffering from lupus or fibromyalgia. Or, for that matter, migraines. What purpose does a migraine serve? Is there any good reason why some subset of the population should have wild horses stampeding in their heads? I can't think of one.
Allergies and intolerances. Why? Again, what purpose? That goes for the common ones--the lactose intolerance, which seems to be everywhere now, and the peanut allergy, which nobody had ever heard of when I was a kid--and the really fun ones that often come in multiples. We once babysat a child who was violently allergic to milk and eggs and something else I can't remember. My wife has cold-induced urticaria, which used to be quite severe and is still something to keep at top of mind in the winter.I know someone else who appears for all the world to be allergic to her own skin; I know of someone else who is allergic to sunlight. Absolutely none of these make sense.
Food. I am far from the only person who laments that there is absolutely no food that is both (a) good for you and (b) actually something you'd want to eat. Sugar, that thing our bodies absolutely crave, is a poison. Not fair, damn it, NOT FAIR.
And all this is to say nothing of the basic structural faults. Who decided to put male genitals on the outside, at perfect kicking height? I'd like to register a complaint regarding the lack of anal musk sacs that should be present in all humans, especially me, to deodorize intestinal gases. I don't particularly care if I lose all my hair--one less thing to deal with in the morning--but a lot of men do care. And I do have to protest that if I do lose all my hair, it simply reappears in my nose, or on my back, or in the crack of my ass...is this really necessary?
You're not supposed to use Q-tips to clean your ears, something I've been doing my entire life. Begs the question of what the hell a Q-tip is actually for. Absent a Q-tip, there should be some simple way to clean your ears. I picture a cowlick: tug it and your ears forcibly eject wax with a sploosh and did I ever just gross my wife out.
Cavities. Couldn't we have designed teeth a little sturdier?
The list just goes on and on. The human body is not a compelling argument for intelligent design.