What's the meaning of the phrase 'Eff off'?
Euphemistic version of 'fuck off'.
What's the origin of the phrase 'Eff off'?
'Eff' is of course the proper spelling of the sixth letter of the alphabet and so, as well as being a euphemism, it is also an abbreviation of 'fuck'.
'Effing' has been known as a euphemism for 'fucking' in the UK from the 1920s. Robert Graves used it in his autobiographical novel Good-bye to all that in 1929. Presumably, for it to be used in that context, it had existed as street slang for some years before 1929.
'Eff off', and 'effing and blinding', were coined a little later. Early examples of them are found in print from the 1940s and, like 'effing', were probably in circulation earlier.
'The f-word' is an American extension of the same euphemism and arose in the 1950s.