It’s not that I encountered it first in a British context; actually, I knew it first as the name of the alcoholic court jester in The Wizard of Id, the cartoon strip by Brant Parker and Johnny Hart (see johnhartstudios.com/wizardofid/characters/index.php?page=bung). It was some time after that that I learned that it was another word for a cork.
But cork is a tight, stopped-up-sounding word, starting and ending with /k/. It’s what you stick in a bottle – you can hear the sound as you push it back into a bottle that (like you) is half drunk (“cork, cork, cork”), or later as you pull it back out (“corrrrk”). Bung is resonant. It’s something you would stick in a barrel, whacking it in with a rubber mallet so the entire vessel makes a “bung!” sound.
Not that that’s where cork comes from, nor – in the case of the stopper – bung. That kind of bung seems to be related to Middle Dutch bonge, meaning the same thing, which may have come ultimately from Latin puncta “hole” (though there are some holes in the etymological trail too). There is also a sense of bung as “dead” (or “bankrupt”) that comes from an Australian Aboriginal language. But some uses of bung do seem to originate in sound symbolism – specifically the senses meaning “throw violently, put forcibly” and “right in the middle of things” – and it’s quite reasonable, I’d say, to think that there is real influence of the sound on all senses (certainly in English usage), just as the “stopper” sense surely has some effect on the non-stopper uses.
At any rate, in Britain the word gets around; they will often say (as Lynne Murphy points out) “My nose is all bunged up” rather than “My nose is all stuffed up,” and they may say, as the Macmillan Dictionary says, “Bung the ball to me, Jack” or “Bring me another beer and just bung it on the bill” – in those senses it’s not merely a real or metaphorical projectile motion that is signified, but specifically a fairly careless one (as may go with the bluntness and dullness of sound of the word – not as focal as bang, let alone bing, nor even as bright as bong). They also use it to refer to bribery and other under-the-table financial payments, as for example secret financial incentives to facilitate a deal in British football (thanks to Lynne for the examples as well).
One may imagine that if you throw a cork (metaphorically) into the middle of a shady transaction in a small house, thereby stopping the action and basically killing it, you could say that you bung a bung bung into the middle of a bung in a bungalow, bunging it up so it’s bung. But that sounds like a bungled jungle of bungs…
I do hope that Lynne Murphy does not find this effort merely echoic of hers. But I thought it a good way to direct you all to her blog and Twitter feed, which are worthy of notice. And it’s a good excuse to move farther afield than just my usual Torontonian perspective.