1. adjective Very busy; preoccupied with many different things at once. Sometimes hyphenated. Primarily heard in Australia. Sorry I couldn't make it to lunch today, I've been flat strap with the kids all day. I've been so flat-strap at work that I barely have time to see my kids anymore.
2. At the greatest possible speed, efficiency, or power. Sometimes hyphenated. Primarily heard in Australia. We drove that car flat strap out of town. The whole team is working flat-strap to get this project finished on time.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.