My grandmother's go-to move is to insult people with things that are so wildly untrue that you have absolutely no way to argue it. Here are my favorites.
  1. He would probably marry you if he had a steady income.
    This was said to my girlfriend. I have a very steady income. My grandmother knows this. But to argue against this opens you up for worse insults.
  2. She would be very pretty if she didn't have those buck teeth.
    Said to my uncle about his now-wife. He made the mistake of arguing, only for her to respond: "well then I just don't know WHAT'S wrong."
  3. That one will have no problem shooting out some kids.
    Said to my father (her son), about and in front of his girlfriend (my mother) the first time they met. While I assume it was a comment on her hips, it literally could not be further from the truth. But who's going to yell about how skinny their hips are? No one. And my grandmother knows that.