The microwave is a great convenience, but there are a few things you should never cook in one. Here are a few of them.
Metal reflects microwave rays, potentially causing fire.
Microwaves can ruin china by igniting metal paint
Anything plastic can melt, leaching estrogen-like chemicals.
4. Breast milk
Scalding pockets of heat can form in microwaved breast milk.
5. Hot peppers
Steam from microwaved hot peppers can damage your eyes.
6. Frozen meat
Meat thawed unevenly can cause food poisoning.
Running an empty microwave will cause it to fry itself.
Improper microwave usage can be fatal - be safe.
Source: Bob Vila