Vestigial Peter

"Vestigial Peter" is the second episode of the twelfth season of, and the 212th episode overall. It first aired on October 6, 2013.

Synopsis
"Peter discovers that he has a vestigial twin, whom he names Chip, growing out of his neck. It's not long before Peter resents the fact that everyone seems to love Chip more than him, so he decides to amputate his twin. However, when Peter gets into trouble, he realizes he needs Chip more than ever."

- The Futon Critic