I actually heard this on sunday night safran on triplej but I heard that these aussie slang words orginated from old christian swear words. I could have the details slightly off but the concept should be correct.

Crikey is a contraction of “Christ Kill Me”

Streuth is a contraction of “God’s Truth”

Bloody is a contraction of “by Our lady” referring the Mary thus “Bloody Mary” cocktail

Blimey is a contraction of “Lord Blind Me”, originally part of the phrase “cor blimey” which was an abbreviation of “may god blind me if it is not so”[1].

Now how could these swear words become so Australian? Cass told me that it is because convicts from England would commonly use these words, which then migrated along with them as they were shipped to Australia for stealing bread and… Saffron.

Reference:
[1]http://english2american.com/dictionary/wholelot.html