Don’t be hurt about it. Some people have to actually get burned to realize fire really will hurt you. Maybe this guy is “hot” who knows? Just be polite and don’t get heated if you can control it. Chances are you could really tick off yur sister and send her over the deep end.
When he arrives, greet him at the door and send him packing by telling him that your sister decided she could no longer date someone who couldn’t think for themselves.