Apparently Alicia Silverstone has canceled her guest appearance on the show due to Britney Spears’ upcoming cameo. As Joel recently reported, Spears pitched the idea herself. She will play a wacky receptionist in a doctor’s office–the doctor was supposed to be played by Silverstone, and she was to appear in a “multi-episode arc”. According to Ausiello, Silverstone quit the gig because she was worried that her performance would be over-shadowed by Britney’s appearance. OK, that’s a legitimate concern. She’s probably right. Although, I think Britney was only going to be on one episode and Silverstone was slated for several.