There'a really funny chapter in "Good Eats" by Alton Brown where he has you make your own microwave popcorn (basically put unpopped kernels in a paper bag). It

There'a really funny chapter in "Good Eats" by Alton Brown where he has you make your own microwave popcorn (basically put unpopped kernels in a paper bag). It contains a long section on whether it's safe to use a staple to keep the popcorn bag shut in the microwave; he structures it as a dialog with his father, who is a physicist. He concludes that this specific instance is not unsafe (if you have a turntable, the mass of the staple is low, etc). But then, I've put grapes in a microwave and produced plasma.