Martin Luther King was a man who wanted white and black have peace with each other without racism another black person can stay another white person can stay with no other way just peace and no violence
Relating these to Australian slang words, if "banger" relates to a sausage, then "cocky" would be short for a cockatoo. A cockatoo is a bird that is a native to Australia. Though "cocky" may also mean someone who is overconfident in a bossy way, seeing as how banger is used as a slang word, cocky as a cockatoo is more fitting.