What is the origin of the idiom "fall flat" and when to use it?

The origin of the idiom "fall flat" is uncertain, but it is believed to be related to the idea of a joke or comedic performance that fails to elicit the desired response from the audience, causing the energy or mood of the performance to "fall flat." Over time, the phrase has come to be used more generally to describe any situation where something fails to achieve the desired outcome, whether it be a joke, a performance, a product launch, or any other situation where success or impact is expected.