I'm not sure if it's an Aussie thing, but if something is suspicious, then it's sus(s), e.g:
Someone added me on Facebook but they don't have a profile picture. I think they're a bit sus(s).
The problem is I don't know whether it is spelt with a double "S". Urban Dictionary has both spellings, and Dictionary.com and others just have "suss" as in "to suss something out".
Could anyone provide a reference?