This maneuver if thats what you Australian parlimentary losers want to call it is when you pretent to shake a womans hand very convincingly but 'accidentally' thrust it into the soft spot between either her tits or legs (depending the relativity of her height and yours).
You only do this if you are confident that you have an AU prime ministers reptilian grin and a "fuck the rest of the country man, only Canberra (where the majority of the politicians live) can smoke dope," mentality.
The Dirty Scomo would be explained by the following convo between copycat surfees who just so happen to watch Australia's favourite crappy 'question time' parlimentary broadcast:
Bruh 1: "duuuuuuuuuuuude, I just saw how SCOMO did a fly handshake where his hand ended up on a chicks tits and bra!"
Bruh 2: "Us surfees need 2 change our tactics unless the surfee kind get wiped out on the next R excuse wave."
Bruh 3 and 4: "nah man, were already charged for that, can't do it even if we tried, plus were in Canberra too busy getting high with Scomo himself, he's gnarly and paid us to be his best friend for like 3 hours while getting baked."