Definition & Meaning of "jit bag"in English

What is the origin of the term "jit bag" and how is it used?

Jit bag is a slang term that appeared in mid-20th-century English to describe a person regarded as contemptible, worthless, or despicable. The term combines "jit," a slang word for a small, insignificant, or foolish person, with "bag" to suggest something useless or disposable. Historically, it was derogatory and insulting, used to belittle or ridicule someone, and today it remains informal and coarse, mainly appearing in mocking or aggressive speech rather than polite contexts.