This was a question posed by a friend. I'm myself curious of the answer. I apologize for the explicit content (I left it as is to remove ambiguity). I pretty sure that 'a yuppy fu@k' is a compound noun in the local slang, but I'm not sure, just like the author of the question, of the nature of the second instance of 'fu@k'. Any feedback will be appreciated.
"Some graffiti I saw in a back lane off Acland Street, St.Kilda:
I'm a yuppy fuck, fuck.
The phrase has stayed with me because of the use of the comma. Is the final word a noun or a verb? Is it an exclamation?"