11. Aluminum Foil
Say it with us: metal doesn’t go in the microwave. It can be easy to forget to remove the foil from your leftovers before popping them in to reheat, but if you do, that food is going up in flames.
12. Nothing
When there’s nothing inside a microwave to absorb the waves, the whole thing can catch on fire. Best case is you damage the appliance. We don’t know why you would, but don’t run your microwave when there’s nothing in it.