Check this wicked article out! Try this at home!!!! Lenzspot told me about this awesome site a year ago and it's been awhile since I've paid a visit.
It's a how to make anything that someone else has already thought of on the cheap using ordinary household items. Need a bycycle powered tennis ball launcher? This place has you covered!
So back to the chocolate. What you do is melt it in your microwave, measure the distance between the two hotspots (showed by melted concave dips on either end of the bar) and this turns out to be half the wavelength emitted by the microwave oven. With the frequency your microwave operates at, which is supposedly 2.45 gigahertz, you do some fancy math and you get a number very close to the speed of light. Pretty frickin amazing!
Then you eat the chocolate after.