In A Pig's Eye Meaning

(idiomatic) Under very unlikely circumstances; probably never.

Example: 2011, Izzy Auld, chapter 64, Aggie's Double Dollies, ISBN 978-1-4620-2496-4, page 366:
  â€œThen he planned to kill you, and take over himself as governor.” “Hah, in a pig's eye,” said Nasty Three.