What it means
To get the sack means to be fired from your job, usually in a blunt, no-frills way. It’s a proper British phrase for being told you’re done and need to clear off, whether that’s for messing up, taking the piss, or the company trimming costs. Even now it still lands with a nice bit of sting.
Usage examples
"Dan got the sack for nicking milk from the office fridge, then blaming the intern. HR didn’t even blink. Now he’s down the pub crying into a packet of crisps."
"He got the sack for taking three-hour lunches, and honestly the only surprise was that it took so long."
"Careful what you post online about the boss, people have got the sack for a lot less than that."
"Maya got the sack after mouthing off at the manager in front of customers, which was brave for about ten seconds and then very jobless."
"If Kev turns up late one more time, he’s getting the sack and nobody in that office will act shocked."
Where it comes from
This one goes back to older British working life. Labourers often kept their tools in a sack, so if the boss handed you your sack, that meant your time was up and you were off the job. The image stuck around, then drifted neatly into modern workplace chat.