He phonetically wrote out how a kiwi would say sharing. Thats literally the joke. Its one of the oldest kiwi jokes in the book.
Edit
I mean this is one of the weirdest things ive seen on the internet.
No its not literally the joke. The joke is the homophonic pun. If he wanted to add a mispronunciation joke to it, he needed to write "sharing" as a "KA-Wee" mispronunciation, not the very same word in reply without inverted commas. Otherwise, he has removed the homophonic pun part of the joke, and just left with the mispronunciation part of the joke - which leaves no sexual jealousy to the sheep. He has turned the homophonic pun of "sharing" and "shearing" into a broken homographic pun of "shearing" and "shearing" where one of the word pair is a made up word. A mispronunciation joke does not fly with bad grammar by the writing. The resulting strict construction of the words suggests there was no misinterpretation at all. If he had written "She-EAR-ring" or "SHE-Air-Ring" or "SHEE- ering" or anything like that, it could have worked. But he didn't. He wrote the one way it could never work, without any sign of inverted commas or any literary device, probably because he had no idea what he was doing. Whether its his inability to spell or his grammar, it is geniused writing.
I do like your idea of the question mark to represent an inflection but I don't think you should use that symbol for that purpose. According to the site below, you certainly should not. It would lead to a nightmare of ambiguity.
http://www.dailywritingtips.com/when-is-a-question-not-a-question/
Straya has become accepted and widely used slang. It is a word. It may not be in the Oxford Dictionary, but its in the urban dictionary.
http://www.buzzfeed.com/alanwhite/the-17-weirdest-things-ever-for-sale-on-the-internet#.awOwLy4Mk
You may not know that before I moved to the UK, I worked on a farm in New Zealand, shearing sheep.
One day I walked into the woolshed and to my horror discovered a workmate being extremely familiar with one of our woolly friends.
'MATE!' I said, 'you're supposed to be SHEARING that sheep!'
With a grin (and a grunt) he replied 'I'm not sharing Matilda with ANYONE!'
