What is the origin of the idiom "phony as a three-dollar bill" and when to use it?

The idiom "phony as a three-dollar bill" likely originated in the United States in the late 19th or early 20th century. During that time, three-dollar bills were not a common denomination in circulation, making them rare and unfamiliar to the general public. Today, it is used to describe someone or something that is fake, fraudulent, or lacks authenticity.