Here's what you need:
Any kind will do really... preferably a cheap one that comes with the apartment--not an expensive one you bought yourself... just in case things go horribly wrong, you won't be stuck with a radioactive microwave after you move out of the apartment.
Really, I only included this picture because I figured out a new setting on my camera where I can manually focus on stuff--it's cool! Anyways... you need a match like this one:
a mason jar
Yes... that is how it sounds in real life!!!
Somehow, by putting a lit match in the microwave, it super-heats the flame and creates a fiery ball of plasma which rises above the burning match. The mason jar is necessary, I assume, to keep the plasma contained & to prevent it from melting the roof off your microwave. I'm a little too scared to try this without the jar. Would it even work? I also haven't had the guts to leave it glowing longer than 5 seconds or so--it's about at that time when the buzzing starts to get MUCH louder and it makes you wonder just what is going on indside there...?? Why don't you try it and let me know how it goes? You can do a blog post about it :)