Other forms: got the sack; getting the sack; gets the sack; gotten the sack
If you get the sack at work, you're fired! Clean off your desk, hand in your badge, empty your locker, and go home. You’ve lost your job, although it may not be through any fault of your own.
The expression get the sack comes from the days when skilled tradespeople, such as carpenters, stoneworkers, or metalworkers, carried their own tools around in a sack from job to job. When they were hired, they'd store these items at their place of employment for convenience, and when they were let go, they'd be given the sack of tools and told to leave. Today, factory workers, office workers, and professionals can all get the sack, often because their employers are downsizing.