Why do I keep thinking about Quentin Tarantino?
I swore black and blue in another thread that Aussies don’t use Seppo as an insult, merely as a cheeky “We’re all mates so it’s olroight” kinda-dealy, but then Mr Cazzle (most upset) told me it most certainly is used by some Australians as a deadly insult and that he’s been on the receiving end more than once (Mr C is Australian but picked up a nasty case of an [endearing] accent while living in the US as a child). So while I’m very uncomfortable about Americans thinking we’re all literally calling them septic tanks and actually thinking that they deserve to be likened to containers of shit when we say Seppos, I guess I have to conceed that there are some amongst us who do. Please try to take it in context though - if your good Aussie mate is having a bit of a laugh with you and calls you a “bloody Seppo” then you probably shouldn’t cut off all contact and consider suing him for damages. If the irate driver you cut off hangs out his window, gives you the finger and yells “Learn to drive you stupid f’ing Seppo” then chances are he’s not doing it out of affection for you. I know at least one person who spent time with an Australian and later found out what Seppo meant and was devastated because they were told that it was only used as a term of insult, but that is not true, and I’m frankly horrified that something that I’ve always considered no more than a bit of fun is actually used by some as a xenophobic insult.
I’m with cazzle regarding the intent behind using Seppo. I have never heard it used as an insult. When I was young and used to come across new rhyming slang words I was always struck by the fact that the best ones = like Seppo - were the most obscure. I certainly can’t think of a catchy, less “offensive” choice. Maybe they are taking whinging lessons from the Poms.
when you say ‘pom’ do you mean ‘pom’ or ‘bloody poms’? likewise is ‘yank’ the polite form of ‘septic’? 
maybe this ‘septic’ thing is exacerbated by brits living abroad??? since i’ve never been to england i’ve got no idea how ‘septic’ is used there, whilst on the other hand i’m pretty clear about brit’s and ‘septic’ in japan hk, china, singapore, etc
i’m certainly willing to concede that in my experience ‘seppo’ has rarely been used in a nasty way (whereas english and ‘septic’ is the reverse). hell, i had an aussie girlfriend i travelled with in china that used ‘shitbum’ as a term of endearment. to be clear, i’m definately insulted by ‘septic’ and completely contextual about ‘seppo’
You know in parts of the Southern U.S. they’d take less offense at the “septic tank” thing, but that “Yankee” reference, on the other hand…
I guess this repulsive term is acceptable here again? A few years ago, users were warned and threatened with banning for using this word. Rightfully so, mind, but really. I’m shocked this thread did not get the lockdown or at least moved to the pit.
I had never seen it written before, and assumed the word was “Burke,” as in “Burke and Hare,” the notorious murderers. Silly me.
If we didn’t use “Septic” for Americans, what other phrase could we use? As Malacandra notes, other phrases rhyming with “Yank” are already taken. He could have added “Barclay’s” (Bank) which, as any of you who have read Kenneth Williams’ diaries will know, is, like Sherman, a wank.
Surely the idea is that there should be no relationship between the rhyming phrase and the object itself, otherwise it would be easier for those not in the know to work it out? Hence the random use of Septic Tank - there is no inference whatsoever about Americans in it: all it does is rhyme with Yank.
And I would imagine that “Seppo” is an Australian invention; I’ve never heard a Brit use it and there is a long tradition of Australians adding O to things (arvo, smoko, garbo, rego etc etc).
“Seppo” is not an insult, but obviously can be used as one - though “bloody seppo arsehole” is probably no different to the speaker than “bloody American arsehole”. Same with “Pom”. In any event, it dates from WWII, and nobody uses it much at all these days. In fact most urban people wouldn’t even know what a septic tank is.
The other thing is that Australian rhyming slang is not used much either. It’s also a bit out-of-date now, and it was never as good as the London version. Some things are best left to the experts.