In a pig's eye!

in a pig's eye

An exclamation of emphatic denial, dissent, or disbelief that something will happen or be true. A: "I'm pretty sure we can restore this old junker in a week. B: "In a pig's eye! That will take months, if not longer!" Step down from the board of directors? In a pig's eye I will!
See also: eye
Farlex Dictionary of Idioms.

In a pig's eye!

 and In a pig's ass!; In a pig's ear!
Rur. Nonsense! (Use caution with ass.) Tom: I wasn't going to steal it. I was just looking at it. Jane: In a pig's eye! I saw you put it in your pocket! Mary: Bill says he's sorry and he'll never yell at me again if I take him back. Jane: In a pig's ass! He's made those promises a hundred times before. Tom: I thought you said I could keep this. Charlie: In a pig's ear! I said you could borrow it.
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.
See also:
  • in a pig's eye
  • (oh,) snap
  • snap
  • Snap!
  • Are you having a laugh?
  • noes
  • oh noes
  • Ye gods and little fishes!
  • hoo-rah
  • viola