Strine for "contagious eccentric to be shunned". The closest seppo equivalent is probably "communist". But then again seppoes are all RatBag(s).
More specifically, a RatBag is someone who isn't shut up when you say NoWorries?.
RatBag can also be used semi-affectionately, just as "Bastard" has 18.5 shades of meaning.
having no clue what this meant, altavista told me +strine +seppo was on http://members.tripod.com/~thisthat/slang.html
it's an aussie slang reference.
according to this document, seppo = American, strine = lots of aussie slang said at once, and ratbag = not a nice person.
See LetStalkStrine.
("Strine" can be thought of as the word "Australian", pronounced with an Australian English accent, the first vowel and 'l' getting lost)
Strictly speaking, only a RatBag would claim RatBags are not nice. The rest of us would say, NoWorries?, they're part of our way of life.
"seppo", of course, is rhyming slang. "Septic Tank" == "Yank".
What about "blighter"?
Likely from "Blighty" for UK, from Urdu "belaiti," European. Not a Strine word, but.