What is the origin of the idiom "come off it" and when to use it?

The idiom "come off it" is an informal expression that is used to indicate skepticism or disbelief when someone makes statements or claims that are considered unrealistic or insincere. While the precise historical origin of the phrase is not documented, it has been in use in everyday language for many years. This expression is used to express skepticism or disbelief when someone is making statements or claims that are considered unrealistic, exaggerated, or insincere.