11 Things You Should Never Put In The Microwave Aluminum Foil. It's nice to see sparks fly, but not so much when it comes to reheating your food. ... Paper Bags. All paper bags are not created equal. ... Plastic Bags and Plastic Containers. ... Travel Mugs. ... Your Favorite Shirt. ... Hard-boiled Eggs. ... Hot Peppers. ... Styrofoam in Microwave. More items...