Back when I was in eighth grade, I ended up reading a Creationist rant written by a wildlife artist in the local newspaper. I didn't have access to handy resources like the Index to Creationist Claims or Pharyngula. I only had my knowledge of 7th grade biology, what I watched on the pre-decay Discovery Channel, and common sense.
He claimed that a ball-and-socket joint couldn't change because changing one without the other would prevent it from working. Cue facepalm. I knew, at least in humans, much of our bones aren't bone during our growth: The "ball" at least, is relatively soft cartilage. If it was oversized, it could probably be worn down to fit better. Additionally, I suspected there could be a gene that covers both, not knowing much about evo-devo. Of course, it wasn't lost on me that if he was right, it could just as easily be used to argue that human growth is impossible. But since human growth is happening all the time, it casts doubt on his hypothesis.
He also made the argument from irreducible complexity, using an airplane as a metaphor. I argued that life is probably more like a cake recipe: A cake recipe that's missing ingredients or cooking steps may not be palatable, but it's still edible. I don't remember what precisely it was about the argument, but I argued that if DNA was as intolerant of change as he seemed to imply, it would rule out reproduction, since just about every time someone or something is conceived, it's a novel combination of genes. After finding out how much "junk" we have, and how little uniqueness we have compared to the overall genome, I don't think it's quite the same. Either way, DNA is pretty tolerant of changes.
He also dipped into the Great Chain of Being straw man, asking why fish aren't evolving into humans. 1. (Humorously posed by my dad) How does he know they aren't? 2. (Serious) They aren't under selective pressure for humanity, so we shouldn't expect them to. He explicitly stated that "linearity is integral to evolution." It's not. It's only linear because we're applying hindsight to it. Evolution can take many paths. The randomness of mutations and chance occurrences can make things turn out differently. There's no program leading to brainy bipeds. That's for sci-fi.
Of course, because Creationism is a dead pseudoscience, this sort of nonsense is still repeated today.