Definition & Meaning of "{one's} (ass|butt) off"

What is the origin of the idiom "one's ass off" and when to use it?

The the exact origin of the idiom "one's ass off" is difficult to pinpoint, but it has been used in casual language for many years, especially in American English to describe someone working extremely hard, putting in a significant amount of effort, or doing something to the maximum extent. The phrase uses a humorous or exaggerated tone, emphasizing the intensity of the effort.