The only thing I microwave is water, in a ceramic mug, for my tea. She's convinced that the microwave "changes the molecular structure" of the water and renders it unsafe.
She sent me this hilarious link:
http://www.relfe.com/microwave.html
Some pretty solid logic there in the first few paragraphs. Someone microwaved blood in a hospital and it killed the transfusion patient. Therefore, microwave = bad.