What is the origin of the idiom "in a pig's eye" and when to use it?

The origin of the idiom "in a pig's eye" is not precisely documented, but it has been in use for many years as a colorful way to convey skepticism or disbelief. It may be related to the idea that pigs have relatively small eyes compared to other animals, which could symbolize a narrow or limited perspective. It is typically used when someone finds a statement or claim to be highly unlikely or not credible.