Origin of bang-upfrom bang (adverb): uncertain or unknown; perhaps from the idea of being up to the mark, meeting a standard of excellence, and the like
Origin of bang-upFrom bang 1
- (idiomatic) Good.
- He’s doing a bang up job.
- In all senses the object may appear before or after the particle. If the object is a pronoun, then it must be before the phrasal verb particle (up).