Get in, bitches: We're going singing. We couldn't believe it when we learned that the Mean Girls musical was not only happening, but opening in Washington, D.C. on 31st October, just in time to bust out our truly scary Cady-inspired Halloween costumes (the scarier, the better). Now we have even more of a reason to celebrate, because the show has finally been cast! If you thought that the Plastics holiday dance was great, wait until you see who's in the show.