1. Physical Labor: The phrase likely originated in the early to mid-20th century, when manual labor was prevalent, and people worked long hours in physically demanding jobs. "Hump" could refer to the back, specifically the thoracic region, which carries the weight of the body during strenuous activity. "Busting" it would suggest pushing oneself to the limit, working tirelessly.
2. Animal Imagery: The word "hump" can also refer to the raised back of a camel, which is known for its ability to carry heavy loads. This association could have strengthened the connection between "busting your hump" and hard work.
3. Colloquial Language: As a phrase, "bust your hump" has a strong informal, colloquial tone, suggesting it might have originated in slang, potentially within specific communities like laborers or athletes.
4. Evolution of Meaning: Over time, the phrase has become more metaphorical, representing any kind of strenuous effort or exertion, not just physical labor. It's used to describe a wide range of tasks, from studying for exams to meeting deadlines.
5. Regional Variation: The phrase's usage and popularity may vary across different regions and demographics.
While the exact origin remains a bit of a mystery, its connection to physical labor, animal imagery, colloquial language, and its evolving meaning makes it a fascinating piece of American slang history.