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.
An exclamatory sentence is a sentence you would be likely to "scream" in the real life: it expressed a great emotion, such as anger or surprise. An exclamatory sentence typically ends with an exclamation mark.
