Definition & Meaning of "the moon is made of (green|) cheese"

What is the origin of the idiom "the moon is made of cheese" and when to use it?

The idiom "the moon is made of cheese" is believed to have originated from various folk tales and fables that date back several centuries. In these stories, the idea of the moon being made of cheese was a whimsical and fantastical idea used to entertain or amuse listeners. It is used to express skepticism, mockingly challenge an unbelievable statement, or simply add a touch of humor to the conversation.