Here is an interesting one

Some years ago I had someone argue that because the Spartans had sent some Greeks home and the residents were saved, if the Spartans hadn't sent those Greeks home all the athenians would have died. I said the athenians might have been abducted by friendly aliens before the Persians arrived, we don't know what would have happened if the Spartans hadn't sent some people to warn athens. I was being facetious but he accused me of using a counterfactual argument. I tried to tell him that he was using the counterfactual argument but he was having none of it. That's when I first realized what a colossal waste of time arguing on the internet is.