It's amazing the number of times a creationist will have a defeater argument for evolution which shows a complete misunderstanding of the process. Questions like "has a cat ever given birth to a dog?" or "where are the half-human half-monkeys?" or "How can the eye come about by chance?" These questions are just so far off the mark, that it's hard to even dignify them with an answer. Perhaps we could ask our own question in rebuttal.
"What's more likely: that every biologist and philosopher over the last 150 years who have spent their careers studying on the subject have missed such an elementary error, or that you might have misunderstood the process?"