Quiet, Grandpa!
It’s one thing to mansplain topics that you are an expert in but some men are overconfident to even mansplain things they know nothing about. This OP’s grandfather had zero idea about cooking, so much so that he couldn’t even make scrambled eggs.
Yet, he thought it was okay to tell his wife how to cook, what pans to use, etc. We get that retirement is boring but maybe he would be better off taking up a hobby or something. Finally, his wife just told him that if he wouldn’t shut up, she would just throw the pan at him. You go, grandma!