DO NOT TRY THIS AT HOME it can ruin your microwave or burn down your house. Now that the warning is out of the way.
slice a grape into quarters
place into microwave (turn on)for no more than 15 seconds
burst of plasma with emminate from the grape
stop microwave to stop reaction (unless you microwave has caught fire, then check out an video-HOW TO PUT OUT A MICROWAVE FIRES)
***you microwave will smell like burn grapes and will be somewhat smokey