If you click on the Etymology Online link in my first reply to this thread, you can see what they say about both of those senses. The plunder sense comes from the idea of putting booty in a bag, and the football sense comes from the plunder sense.
–Mark
Yup. I’m familiar with the word “sacked” as it relates to getting fired.
At least any American who has read the credits in Monty Python and the Holy Grail.
It is in Finance too, as it renders you unable to screw with accounts and inventory.
I’ve heard the term “sacked” many times in this context. As much or maybe more than “canned”.
I grew up (and still live) in the Pacific Northwest. I thought it was a common term in the US.
And collecting your things isn’t cold or rare… What else are you going to do with personal items? Whether you’re being escorted out by security or leaving on your own terms you need to carry them out somehow. A box is probably the most convenient way.
What would be cold is confiscating an employee’s personal effects after they’re terminated. Which I’ve never heard of luckily.
In all my years of office employment the only personal article I had on the job was a copy of Annotations to Finnegans Wake, and that was for one truly sucky job.
I’m not sure what that says about me.
“Take your things if you want to live.” 
I can’t say where I first heard it. I work with a some Brits now but I’m sure I’ve known this term for a long time. It’s possible I first picked it up watching BBC shows like Monty Python way back when, I just can’t say I know of a time when I didn’t know what it meant. One problem is that it’s meaning is obvious in context.
I see. Thank you. (Now I’m wondering where “canned” comes from!)
Yeah, I was a kid when I saw ‘sacked’ for the first time in Holy Grail in '76 and I didn’t know what it meant (it’s actually in the opening credits, the film has no ending credits). Sort of because I didn’t know what it actually meant and because I was a kid it still seemed funny (like they were actually put in a sack or something)…
“Those responsible for the previous sackings, have been sacked…”
It’s a US usage. Probably the original sense was “thrown in the trashcan”; hence, “discarded”, hence “dismissed”. “Can it!” in the sense of “stop that behaviour” is also a US usage, and probably has a similar derivation. Both turn up the early twentieth century.
“Canned” is one of those words that can have almost diametrically opposed senses - “canned” meaning discarded versus “canned” meaning preserved. The first sense derives from trashcan, of course, and the second from cans or cannisters used to keep things. A sound or film recording which has been “canned” has been completed, not discarded, and of course we have canned laughter. But I think the “discard” sense is gradually eclipsing the “preserve” sense.
In most of the rest of the anglosphere, things are discarded in dustbins, not trashcans, and they are preserved in tins, not cans, so these usages have limited penetration outside US English, and other variants influenced by US English.
I did a lot of work with NCR in the 90’s. They would tell you that "you’re fired"come from the former head of NCR who when getting rid of a particular employee, dragged his desk out too and set fire to it.
sorry, no cite & not sure whether it’s not an urban legend…
Do the Brits still use the word “tip” for trash? (It’s in the Wake often, since I mentioned it.)
Even ignoring the absurdity of a company destroying valuable property for no reason, the word “fired” in the “dismissed from work” sense dates from 1885 (cite). NCR was founded in 1884, but it’s highly unlikely that (a) a lot of people were fired within the first year, (b) that the bizarre practice of burning their desk developed in that short time, (c) that the company was successful enough in their first year that they could afford to frivolously destroy desks, and (d) that the idea spread and became a widely known expression among the general population in that short time.
–Mark
To drive a stake through the heart of that canard, the OED now has an 1879 cite–
I’m disappointed. I was hoping it went back to the Roman punishment (for parracide) of literally sewing someone into a sack with several animals and throwing them into the Tiber, there to drown.