blow in the bag

English

Etymology

From the previous use of a plastic bag over the end of a breathalyser, to measure a specific amount of breath.

Verb

blow in the bag (third-person singular simple present blows in the bag, present participle blowing in the bag, simple past blew in the bag, past participle blown in the bag)

1. (informal, dated) To supply a specimen of breath for alcohol analysis.