Um...I have done that before. It gets all sparkley, and leaves burn marks inside the microwave. It might do more than that if left in there longer, but I never tried, since it was already starting to damage the microwave.
So I don't understand this meme. Is there a newer kind of microwave that can handle aluminum foil safely that I just don't know about? Or am I just too much like an NPC to get the joke?