For the record, my friends across the hall last year microwaved dozens upon dozens of cds in their microwave.
If you're going to do this, be sure to:
  • Place the cd on a paper plate, both to avoid having the cd actually touch the walls of the microwave, and to collect the little pieces of aluminum
  • Only do it for about 4 seconds... the pretty lights stop after that much time, and the chances you'll fuck up your microwave probably increase as well
  • Don't bother putting more than one cd in at a time... the microwaves get spread out, and each cd is less interesting to look at
Also, don't stand around and breathe in real deeply when you open the microwave door, as there will be a rich aroma from melting plastic in the cd. And as always, don't stand directly in front of a microwave while it's operating, or in 30 years you'll get prostate cancer.