Raw prawn; ripoff & Hoodwink

This is one of my all time favourites. I've only ever heard it used in my own country - Australia and by Australians. However, it wouldn't surprise me if it's originally Cockney or something.

For those who haven't heard it, it seems to mean 'don't try to hoodwink me' (hoodwink - there's another one), or don't try to rip me off (yet another one - rip me off).

So can anyone help with this one, or even 'hoodwink' & 'rip me off'.

Thanks,
Petalyn (yep, that's my real name, not Lotg)

From Eric Partridge, Dictionary of Catch Phrases: American and British, from the Sixteenth Century to the Present Day:
"don't come the raw prawn!" 'Don't try to put one over me!' --'Don't try to impose on me!' This catchphrase arose, during WW2, in the Australian Army; Wilkes's earliest printed date is 1942; in 1946 Rohan Rivett, 'Behind Bamboo' (a prisoner-of-war story) writes, '"Raw prawn" something far-fetched, difficult to swallow, absurd'. Apparently first dictionaried by the late Grahame Johnston, in 'The Australian Pocket Oxford Dictionary', 1976. A raw prawn is less edible than a cooked one. [Paul Beale, who edited and revised Partridge's book:] if in fact to do with cooking, then perhaps orig. a ref. to the Japanese delicacy. I have also heard the phrase used to mean 'Don't pretend to be the naive innocent!'

End of Partridge quote; back to me (R.B.): I first heard "rip off" (verb) and "ripoff" (noun) in the US, 1960s. As far as I know, they started as hippie slang.

These following words, including 'Hoodwink', come from the ancient sport of falconry, which has left several marks on the English language:
Fed up - trained hawks are driven by appetite: one which has 'fed up' wants merely to sit still and digest its meal (ie it is totally unresponsive).
Gorged - a hawk's crop is in its throat (le gorge in French).
Chaperone and hoodwink - blindfolding a hawk with a hood (chaperone in French) calms it by making it think it is night. This reduces the risk of impetuous behaviour.
Booze - hawks were traditionally trapped in Holland and needed to drink (?boozen? in Dutch) on the sea crossing to England.
Haggard - an older hawk, caught in adult plumage. Although falconers used to prize such birds, haggard and hag are definitely derogatory when applied to humans.
Cadge - a mobile perch on which falcons are carried. The unpaid bearer would have to 'cadge' tips from onlookers.